security: fix four vulnerabilities (GHSA-779p-m5rp-r4h4) (#14734)

* security: fix five vulnerabilities (GHSA-779p-m5rp-r4h4)

- CVE-2026-56670: force download of SVG/XML responses on /view to prevent stored XSS
- CVE-2026-56671: contain /experiment/models/preview reads within the model folder
- CVE-2026-56672: stop inline rendering of uploaded /userdata/{file} content
- CVE-2026-56673: prevent path traversal in get_annotated_filepath (LoadImage /prompt input)
- CVE-2026-56674: reject opaque/null Origin to close the CSRF middleware bypass

Adds regression tests under tests-unit/security_test/ covering all five.

* security: address review feedback on GHSA-779p fixes

- Fix Windows CI failure in test_get_annotated_filepath: compare against
  os.path.abspath(...) to match the intentional abspath normalization added
  by the traversal hardening (abspath prepends the drive letter on Windows).
- origin_check: narrow the bare `except:` in is_loopback() to ValueError so
  genuine interrupts aren't swallowed (review nit).
- origin_check: guard .port access in is_cross_origin_forbidden() so a
  malformed/out-of-range port (e.g. Origin: http://127.0.0.1:99999) fails
  closed with a 403 instead of surfacing an uncaught 500 in the middleware.
- server /view: escape backslash/quote in the Content-Disposition filename
  (RFC 6266 quoted-string) so a filename containing a double quote can't
  malform the response header.

* security: address CodeRabbit review feedback on GHSA-779p tests

- test #3: guard the symlink-escape test with a try/except skip so it no
  longer errors on Windows CI where os.symlink needs elevated privileges /
  Developer Mode (mirrors the guard in the sibling test #2).
- test #5: refresh the stale module docstring to describe the actual /view
  gating (view_image closure calling folder_paths.is_dangerous_content_type,
  the normalising check) instead of the bypassable raw set-membership test.

* revert(security): drop CVE-2026-56674 Origin: null CSRF change

Per maintainer review, the reported CSRF is already mitigated by the pre-existing
Sec-Fetch-Site: cross-site check for current browsers, and the null-origin
rejection risked breaking legitimate sandboxed-iframe embeds. Restores
origin_only_middleware and is_loopback in server.py to their prior state
(the Sec-Fetch-Site check is retained) and removes utils/origin_check.py and its
regression test. The other four GHSA-779p fixes are unaffected.

tests-unit/security_test/test_ghsa_779p_02_preview_traversal.py

@@ -0,0 +1,192 @@
+"""CI unit tests for FIX #2 of GHSA-779p-m5rp-r4h4.
+
+Path traversal / hardening in app/model_manager.py get_model_preview
+(route /experiment/models/preview/{folder}/{path_index}/{filename:.*}).
+
+Reference: https://github.com/Comfy-Org/ComfyUI/security/advisories/GHSA-779p-m5rp-r4h4
+"""
+import pytest
+import yarl
+from io import BytesIO
+from PIL import Image
+from aiohttp import web
+from unittest.mock import patch
+from app.model_manager import ModelFileManager
+
+pytestmark = (
+    pytest.mark.asyncio
+)  # This applies the asyncio mark to all test functions in the module
+
+@pytest.fixture
+def model_manager():
+    return ModelFileManager()
+
+@pytest.fixture
+def app(model_manager):
+    app = web.Application()
+    routes = web.RouteTableDef()
+    model_manager.add_routes(routes)
+    app.add_routes(routes)
+    return app
+
+
+async def test_legit_preview_returns_200(aiohttp_client, app, tmp_path):
+    """Sanity: a real preview PNG inside the model folder is served as webp 200."""
+    img = Image.new('RGB', (16, 16), color=(255, 0, 128))
+    img.save(tmp_path / "test_model.png", format='PNG')
+
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get('/experiment/models/preview/test_folder/0/test_model.png')
+
+        assert response.status == 200
+        assert response.content_type == 'image/webp'
+
+        img_bytes = BytesIO(await response.read())
+        served = Image.open(img_bytes)
+        assert served.format
+        assert served.format.lower() == 'webp'
+        served.close()
+
+
+async def test_non_integer_path_index_returns_400(aiohttp_client, app, tmp_path):
+    """A non-integer path_index segment must be rejected with 400."""
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get('/experiment/models/preview/test_folder/abc/test_model.png')
+
+        assert response.status == 400
+
+
+async def test_out_of_range_path_index_returns_404(aiohttp_client, app, tmp_path):
+    """A path_index beyond the configured folder list must return 404."""
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get('/experiment/models/preview/test_folder/99/test_model.png')
+
+        assert response.status == 404
+
+
+async def test_empty_filename_returns_400(aiohttp_client, app, tmp_path):
+    """The "{filename:.*}" capture also matches the empty string (trailing
+    slash). It would resolve to the folder itself and must be rejected with 400."""
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get('/experiment/models/preview/test_folder/0/')
+
+        assert response.status == 400
+
+
+async def test_path_traversal_in_filename_returns_403(aiohttp_client, app, tmp_path):
+    """Path traversal in {filename} must be rejected with 403 and must NOT read
+    a file outside the configured model directory.
+
+    GOTCHA: aiohttp/yarl collapses literal ``../`` dot-segments out of the URL
+    path before it reaches the handler, which would make this test vacuously
+    pass (the request would hit a different/non-existent route). We percent-encode
+    the dots and slashes (``%2e%2e%2f``) and send the URL with
+    ``yarl.URL(..., encoded=True)`` so the bytes survive client-side normalization
+    untouched; aiohttp's router then percent-decodes them into ``match_info``,
+    delivering the literal ``../`` traversal to the handler's ``{filename:.*}``
+    capture.
+
+    Without the fix the handler computes
+    ``os.path.normpath(os.path.join(folder, "../../../../etc/hosts"))``, which
+    escapes ``tmp_path`` and would be passed straight to get_model_previews ->
+    Image.open, serving bytes from outside the model dir (200/served bytes). The
+    is_within_directory() containment check is the load-bearing fix that turns
+    that escape into a 403.
+    """
+    # Sanity-anchor: a legit preview exists inside tmp_path, so a 200 path is
+    # genuinely reachable — proving the 403 below is the containment check
+    # firing, not an unrelated 404.
+    img = Image.new('RGB', (16, 16), color=(255, 0, 128))
+    img.save(tmp_path / "test_model.png", format='PNG')
+
+    # Percent-encoded "../../../../etc/hosts" so yarl does not collapse the
+    # dot-segments before the request leaves the client.
+    encoded_traversal = '%2e%2e%2f' * 4 + 'etc%2fhosts'
+    raw_path = '/experiment/models/preview/test_folder/0/' + encoded_traversal
+    url = yarl.URL(raw_path, encoded=True)
+
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get(url)
+
+        # Confirm the traversal actually reached the handler intact: a 200 here
+        # would mean either normalization stripped the ``../`` (vacuous pass) or
+        # the containment check failed open and served outside-dir bytes.
+        assert response.status == 403, (
+            f"expected 403 from is_within_directory() containment check, "
+            f"got {response.status}; traversal may have been normalized away "
+            f"or the fix failed open"
+        )
+        body = await response.read()
+        assert body == b"", "403 response must not carry any file bytes"
+
+
+async def test_symlink_companion_preview_returns_403(aiohttp_client, app, tmp_path):
+    """A companion preview file is selected by a glob inside get_model_previews
+    and then opened. If that companion is a symlink whose path is in-dir but
+    whose target escapes the model folder, it must be rejected with 403 — not
+    served. The requested path itself stays in-dir (so the first containment
+    check passes); the load-bearing fix is the SECOND is_within_directory check
+    on the file actually opened.
+    """
+    model_dir = tmp_path / "models"
+    model_dir.mkdir()
+    secret_dir = tmp_path / "secret"
+    secret_dir.mkdir()
+    # A real image OUTSIDE the model dir — valid, so without the fix Image.open
+    # would succeed and its bytes would be served (200).
+    secret = secret_dir / "secret.png"
+    Image.new('RGB', (8, 8), color=(0, 0, 0)).save(secret, format='PNG')
+    # Companion preview, in-dir by name but a symlink escaping the model dir.
+    # (No real model file is needed — get_model_previews globs companions by
+    # basename, and omitting a .safetensors avoids the metadata-header read.)
+    companion = model_dir / "model.preview.png"
+    try:
+        companion.symlink_to(secret)
+    except (OSError, NotImplementedError):
+        pytest.skip("symlinks not supported on this platform/filesystem")
+
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(model_dir)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get('/experiment/models/preview/test_folder/0/model.safetensors')
+
+        assert response.status == 403, (
+            f"expected 403 — the globbed companion preview is a symlink resolving "
+            f"outside the model dir and must not be served; got {response.status}"
+        )
+        assert await response.read() == b""
+
+
+async def test_null_byte_in_filename_no_500(aiohttp_client, app, tmp_path):
+    """A NUL byte in the filename must yield a clean client rejection, not a 500
+    from an uncaught ValueError in is_within_directory's realpath() call."""
+    raw_path = '/experiment/models/preview/test_folder/0/' + 'a%00b'
+    url = yarl.URL(raw_path, encoded=True)
+
+    with patch('folder_paths.folder_names_and_paths', {
+        'test_folder': ([str(tmp_path)], None)
+    }):
+        client = await aiohttp_client(app)
+        response = await client.get(url)
+
+        assert response.status != 500, (
+            f"NUL byte produced a 500 (uncaught ValueError); expected a clean "
+            f"4xx rejection, got {response.status}"
+        )
+        assert 400 <= response.status < 500

tests-unit/security_test/test_ghsa_779p_03_annotated_traversal.py

@@ -0,0 +1,165 @@
+"""Security tests for GHSA-779p-m5rp-r4h4 — FIX #3.
+
+Path traversal in folder_paths.get_annotated_filepath / exists_annotated_filepath,
+plus the shared is_within_directory() containment helper.
+
+These are pure-function tests (no running server). The input/output/temp
+directories are pointed at tmp_path via the folder_paths setters, so a crafted
+name containing `../`, an absolute path, or a symlink that escapes the base
+directory must be rejected.
+
+Reference: https://github.com/Comfy-Org/ComfyUI/security/advisories/GHSA-779p-m5rp-r4h4
+"""
+import os
+
+import pytest
+
+import folder_paths
+from comfy.options import enable_args_parsing
+enable_args_parsing()
+
+
+@pytest.fixture
+def sandbox(tmp_path):
+    """Point folder_paths' input/output/temp dirs at a real temp sandbox.
+
+    Yields the realpath'd base, input, output and temp directories. The original
+    directory values are restored afterward so tests stay isolated.
+    """
+    base = os.path.realpath(str(tmp_path))
+    input_dir = os.path.join(base, "input")
+    output_dir = os.path.join(base, "output")
+    temp_dir = os.path.join(base, "temp")
+    for d in (input_dir, output_dir, temp_dir):
+        os.makedirs(d, exist_ok=True)
+
+    orig_input = folder_paths.get_input_directory()
+    orig_output = folder_paths.get_output_directory()
+    orig_temp = folder_paths.get_temp_directory()
+
+    folder_paths.set_input_directory(input_dir)
+    folder_paths.set_output_directory(output_dir)
+    folder_paths.set_temp_directory(temp_dir)
+
+    yield {
+        "base": base,
+        "input": input_dir,
+        "output": output_dir,
+        "temp": temp_dir,
+    }
+
+    folder_paths.set_input_directory(orig_input)
+    folder_paths.set_output_directory(orig_output)
+    folder_paths.set_temp_directory(orig_temp)
+
+
+# ---------------------------------------------------------------------------
+# is_within_directory() — the shared containment helper
+# ---------------------------------------------------------------------------
+
+def test_is_within_directory_legit_child(sandbox):
+    base = sandbox["input"]
+    child = os.path.join(base, "sub", "image.png")
+    assert folder_paths.is_within_directory(base, child) is True
+
+
+def test_is_within_directory_dotdot_escape(sandbox):
+    base = sandbox["input"]
+    escape = os.path.join(base, "..", "..", "etc", "passwd")
+    assert folder_paths.is_within_directory(base, escape) is False
+
+
+def test_is_within_directory_symlink_escape(sandbox):
+    """A symlink created INSIDE base that points OUTSIDE base must not pass.
+
+    This is the key new hardening: is_within_directory realpath()s both operands,
+    so a symlink planted in the base directory can't be used to read files
+    elsewhere. We create a real on-disk symlink and a real secret target to
+    verify the check actually resolves the link.
+    """
+    base = sandbox["input"]
+
+    # A directory living outside the base, holding a secret file.
+    outside = os.path.join(sandbox["base"], "outside_secret_dir")
+    os.makedirs(outside, exist_ok=True)
+    secret = os.path.join(outside, "secret.txt")
+    with open(secret, "w") as f:
+        f.write("top secret")
+
+    # Plant a symlink inside base that points at the outside directory.
+    # symlink creation can require elevated privileges / Developer Mode on
+    # Windows, so skip cleanly where it isn't available (same guard as the
+    # sibling test in test_ghsa_779p_02_preview_traversal.py).
+    link = os.path.join(base, "escape_link")
+    try:
+        os.symlink(outside, link)
+    except (OSError, NotImplementedError):
+        pytest.skip("symlinks not supported on this platform/filesystem")
+
+    # Accessing the secret "through" the in-base symlink must be rejected.
+    target_via_link = os.path.join(link, "secret.txt")
+    assert folder_paths.is_within_directory(base, target_via_link) is False
+
+
+# ---------------------------------------------------------------------------
+# get_annotated_filepath()
+# ---------------------------------------------------------------------------
+
+def test_get_annotated_filepath_legit_name(sandbox):
+    result = folder_paths.get_annotated_filepath("image.png")
+    assert result == os.path.join(sandbox["input"], "image.png")
+    assert folder_paths.is_within_directory(sandbox["input"], result)
+
+
+def test_get_annotated_filepath_input_annotation(sandbox):
+    result = folder_paths.get_annotated_filepath("image.png [input]")
+    assert result == os.path.join(sandbox["input"], "image.png")
+
+
+def test_get_annotated_filepath_output_annotation(sandbox):
+    result = folder_paths.get_annotated_filepath("image.png [output]")
+    assert result == os.path.join(sandbox["output"], "image.png")
+
+
+def test_get_annotated_filepath_temp_annotation(sandbox):
+    result = folder_paths.get_annotated_filepath("image.png [temp]")
+    assert result == os.path.join(sandbox["temp"], "image.png")
+
+
+def test_get_annotated_filepath_dotdot_raises(sandbox):
+    with pytest.raises(ValueError):
+        folder_paths.get_annotated_filepath("../etc/passwd")
+
+
+def test_get_annotated_filepath_dotdot_with_annotation_raises(sandbox):
+    with pytest.raises(ValueError):
+        folder_paths.get_annotated_filepath("../../etc/passwd [output]")
+
+
+def test_get_annotated_filepath_absolute_escape_raises(sandbox):
+    with pytest.raises(ValueError):
+        folder_paths.get_annotated_filepath("/etc/passwd")
+
+
+# ---------------------------------------------------------------------------
+# exists_annotated_filepath()
+# ---------------------------------------------------------------------------
+
+def test_exists_annotated_filepath_existing_legit_file(sandbox):
+    real = os.path.join(sandbox["input"], "real.png")
+    with open(real, "w") as f:
+        f.write("data")
+    assert folder_paths.exists_annotated_filepath("real.png") is True
+
+
+def test_exists_annotated_filepath_traversal_returns_false(sandbox):
+    """A traversal name must return False without raising and without probing
+    outside the base directory (must never reach os.path.exists for the escape).
+    """
+    # /etc/passwd exists on POSIX; the function must still report False because
+    # the resolved path escapes the input directory.
+    assert folder_paths.exists_annotated_filepath("../../../../../../etc/passwd") is False
+
+
+def test_exists_annotated_filepath_absolute_returns_false(sandbox):
+    assert folder_paths.exists_annotated_filepath("/etc/passwd") is False

tests-unit/security_test/test_ghsa_779p_04_userdata_xss.py

@@ -0,0 +1,147 @@
+"""
+CI unit tests for FIX #4 of GHSA-779p-m5rp-r4h4.
+
+Stored-XSS hardening on GET /userdata/{file} in app/user_manager.py.
+
+User data files are arbitrary user-supplied content and must never render
+inline in the app origin. The getuserdata handler:
+  - forces Content-Type to application/octet-stream for any type in
+    folder_paths.DANGEROUS_CONTENT_TYPES (text/html, image/svg+xml,
+    text/javascript, ...),
+  - sets X-Content-Type-Options: nosniff,
+  - sets Content-Disposition: attachment.
+
+These tests pre-create files in tmp_path and GET them back, asserting the
+secure response headers. They mirror the aiohttp_client pattern in
+tests-unit/prompt_server_test/user_manager_test.py.
+"""
+
+import pytest
+import os
+from aiohttp import web
+from app.user_manager import UserManager
+
+pytestmark = (
+    pytest.mark.asyncio
+)  # This applies the asyncio mark to all test functions in the module
+
+
+@pytest.fixture
+def user_manager(tmp_path):
+    um = UserManager()
+    um.get_request_user_filepath = lambda req, file, **kwargs: os.path.join(
+        tmp_path, file
+    ) if file else tmp_path
+    return um
+
+
+@pytest.fixture
+def app(user_manager):
+    app = web.Application()
+    routes = web.RouteTableDef()
+    user_manager.add_routes(routes)
+    app.add_routes(routes)
+    return app
+
+
+async def test_html_served_as_octet_stream(aiohttp_client, app, tmp_path):
+    (tmp_path / "evil.html").write_text(
+        "<script>console.log('xss-marker-ghsa-779p')</script>"
+    )
+
+    client = await aiohttp_client(app)
+    resp = await client.get("/userdata/evil.html")
+
+    assert resp.status == 200
+    ct = resp.headers.get("Content-Type", "")
+    # The load-bearing assertion: a .html file must NOT be served as text/html.
+    assert "text/html" not in ct.lower(), (
+        f"Content-Type {ct!r} would let a browser render/execute the file (stored XSS)."
+    )
+    assert ct == "application/octet-stream"
+    assert resp.headers.get("X-Content-Type-Options") == "nosniff"
+    assert "attachment" in resp.headers.get("Content-Disposition", "")
+
+
+async def test_svg_served_as_octet_stream(aiohttp_client, app, tmp_path):
+    (tmp_path / "evil.svg").write_text(
+        '<?xml version="1.0"?>'
+        '<svg xmlns="http://www.w3.org/2000/svg">'
+        '<script>console.log("xss-marker-ghsa-779p")</script>'
+        "</svg>"
+    )
+
+    client = await aiohttp_client(app)
+    resp = await client.get("/userdata/evil.svg")
+
+    assert resp.status == 200
+    ct = resp.headers.get("Content-Type", "")
+    # SVG can carry inline <script>; it must not be served as image/svg+xml.
+    assert "svg" not in ct.lower(), (
+        f"Content-Type {ct!r} would let a browser render the SVG and execute embedded scripts."
+    )
+    assert ct == "application/octet-stream"
+    assert resp.headers.get("X-Content-Type-Options") == "nosniff"
+    assert "attachment" in resp.headers.get("Content-Disposition", "")
+
+
+async def test_js_served_as_octet_stream(aiohttp_client, app, tmp_path):
+    (tmp_path / "evil.js").write_text("alert('xss-marker-ghsa-779p')")
+
+    client = await aiohttp_client(app)
+    resp = await client.get("/userdata/evil.js")
+
+    assert resp.status == 200
+    ct = resp.headers.get("Content-Type", "").lower()
+    # Must not be served as any executable JavaScript content type.
+    assert "javascript" not in ct, (
+        f"Content-Type {ct!r} is an executable JS type."
+    )
+    assert "ecmascript" not in ct, (
+        f"Content-Type {ct!r} is an executable JS type."
+    )
+    assert ct == "application/octet-stream"
+    assert resp.headers.get("X-Content-Type-Options") == "nosniff"
+    assert "attachment" in resp.headers.get("Content-Disposition", "")
+
+
+async def test_xml_dialect_served_as_octet_stream(aiohttp_client, app, tmp_path):
+    """An XML dialect outside the original blocklist (.xslt -> application/xslt+xml)
+    must still be forced to download. This pins the normalised *+xml family rule
+    in folder_paths.is_dangerous_content_type(); a plain set-membership test would
+    have served this inline."""
+    (tmp_path / "evil.xslt").write_text(
+        '<?xml version="1.0"?>'
+        '<xsl:stylesheet version="1.0" '
+        'xmlns:xsl="http://www.w3.org/1999/XSL/Transform">'
+        "<!-- xss-marker-ghsa-779p -->"
+        "</xsl:stylesheet>"
+    )
+
+    client = await aiohttp_client(app)
+    resp = await client.get("/userdata/evil.xslt")
+
+    assert resp.status == 200
+    ct = resp.headers.get("Content-Type", "")
+    assert ct == "application/octet-stream", (
+        f"Content-Type {ct!r}: an *+xml dialect must be forced to octet-stream "
+        f"(it can carry inline script via stylesheet/entity tricks)."
+    )
+    assert resp.headers.get("X-Content-Type-Options") == "nosniff"
+    assert "attachment" in resp.headers.get("Content-Disposition", "")
+
+
+async def test_benign_txt_still_served(aiohttp_client, app, tmp_path):
+    (tmp_path / "note.txt").write_text("just a harmless note")
+
+    client = await aiohttp_client(app)
+    resp = await client.get("/userdata/note.txt")
+
+    assert resp.status == 200
+    assert await resp.text() == "just a harmless note"
+    ct = resp.headers.get("Content-Type", "")
+    # text/plain is not in the dangerous set, so it is acceptable here. The
+    # defence-in-depth headers must still be present regardless.
+    assert "text/plain" in ct.lower()
+    assert resp.headers.get("X-Content-Type-Options") == "nosniff"
+    assert "attachment" in resp.headers.get("Content-Disposition", "")

tests-unit/security_test/test_ghsa_779p_05_dangerous_content_types.py

@@ -0,0 +1,138 @@
+"""CI unit guard for FIX #5 of GHSA-779p-m5rp-r4h4 — the /view forced-download set.
+
+Vuln #5 was stored XSS via SVG upload: the /view endpoint's Content-Type
+blocklist covered text/html, text/javascript, etc. but was missing
+image/svg+xml, so an uploaded SVG carrying an inline <script> was served as
+image/svg+xml and executed in the page origin when rendered.
+
+The /view forced-download decision lives in the view_image closure registered by
+server.PromptServer.add_routes (server.py ~line 596), which calls
+`folder_paths.is_dangerous_content_type(content_type)` — a normalising check that
+strips charset/boundary parameters and casing and folds in the whole */xml and
+*+xml dialect family — rather than a bypassable raw
+`content_type in folder_paths.DANGEROUS_CONTENT_TYPES` membership test. On a match
+it rewrites the response to application/octet-stream with a
+Content-Disposition: attachment header. server.py cannot be imported in a unit
+test (importing it spins up the full PromptServer/aiohttp app and its global side
+effects), so these tests pin the underlying dangerous-content data
+(folder_paths.DANGEROUS_CONTENT_TYPES) and the normalising is_dangerous_content_type()
+helper that the closure actually calls.
+
+The end-to-end /view assertion (upload an SVG, GET /view, confirm the response
+is not served as image/svg+xml) lives in the live POC at
+.security/pocs/test_security_ghsa_779p.py::TestViewSvgContentType, which
+requires a running server. This file is the fast, server-free CI guard on the
+set contents so the blocklist can't silently regress.
+"""
+
+import folder_paths
+
+
+# Active/renderable content types that must be forced to download. Each of these
+# can carry an inline <script> (or otherwise execute) in the page origin if a
+# browser renders it. image/svg+xml is the original missing item that caused
+# vuln #5.
+DANGEROUS = [
+    'image/svg+xml',
+    'application/xml',
+    'text/xml',
+    'text/html',
+    'text/html-sandboxed',
+    'application/xhtml+xml',
+    'text/javascript',
+    'application/javascript',
+    'application/x-javascript',
+    'application/ecmascript',
+    'text/css',
+]
+
+# Benign image types that browsers display inline and that must keep rendering;
+# forcing these to download would break legitimate previews.
+BENIGN_INLINE_IMAGES = [
+    'image/png',
+    'image/jpeg',
+    'image/webp',
+    'image/gif',
+]
+
+
+def test_dangerous_content_types_is_a_set():
+    assert isinstance(folder_paths.DANGEROUS_CONTENT_TYPES, set)
+
+
+def test_svg_is_in_the_blocklist():
+    """The specific item whose absence caused vuln #5."""
+    assert 'image/svg+xml' in folder_paths.DANGEROUS_CONTENT_TYPES, (
+        "image/svg+xml missing from DANGEROUS_CONTENT_TYPES — this is exactly "
+        "the regression that reopens GHSA-779p-m5rp-r4h4 vuln #5 (stored XSS "
+        "via SVG upload on /view)."
+    )
+
+
+def test_all_dangerous_types_present():
+    missing = [ct for ct in DANGEROUS if ct not in folder_paths.DANGEROUS_CONTENT_TYPES]
+    assert not missing, (
+        f"DANGEROUS_CONTENT_TYPES is missing required active/renderable types: "
+        f"{missing}. The /view closure only forces a download for content types "
+        f"in this set; anything missing here is served inline and can execute."
+    )
+
+
+def test_benign_inline_image_types_absent():
+    leaked = [ct for ct in BENIGN_INLINE_IMAGES if ct in folder_paths.DANGEROUS_CONTENT_TYPES]
+    assert not leaked, (
+        f"Benign inline-displayable image types found in DANGEROUS_CONTENT_TYPES: "
+        f"{leaked}. Forcing these to download would break legitimate image "
+        f"previews in /view — they must keep rendering inline."
+    )
+
+
+# ---------------------------------------------------------------------------
+# is_dangerous_content_type() — the normalising check the /view and /userdata
+# handlers now call instead of a raw `in DANGEROUS_CONTENT_TYPES` membership
+# test. An exact-string membership test was bypassable with a charset parameter
+# or odd casing, and missed the wider XML dialect family; these tests pin the
+# normalisation so that bypass can't reopen.
+# ---------------------------------------------------------------------------
+
+def test_function_matches_plain_dangerous_types():
+    for ct in DANGEROUS:
+        assert folder_paths.is_dangerous_content_type(ct) is True, ct
+
+
+def test_function_strips_parameters_and_casing():
+    """A charset/boundary parameter or casing must not slip a type past the check.
+
+    This is the bypass surfaced by review: the /view blake3 branch can serve an
+    attacker-controlled, unvalidated asset mime_type like 'text/html; charset=utf-8',
+    which an exact-string set test missed.
+    """
+    for ct in (
+        'text/html; charset=utf-8',
+        'TEXT/HTML',
+        'Text/HTML; charset=UTF-8',
+        'image/svg+xml; charset=utf-8',
+        '  text/html  ',
+    ):
+        assert folder_paths.is_dangerous_content_type(ct) is True, ct
+
+
+def test_function_covers_xml_dialect_family():
+    """Any *+xml / */xml dialect is dangerous without enumerating each one."""
+    for ct in (
+        'application/xslt+xml',
+        'application/rss+xml',
+        'application/atom+xml',
+        'application/rdf+xml',
+        'application/mathml+xml',
+        'message/rfc822',
+    ):
+        assert folder_paths.is_dangerous_content_type(ct) is True, ct
+
+
+def test_function_allows_benign_and_empty():
+    for ct in BENIGN_INLINE_IMAGES + ['application/octet-stream', 'text/plain']:
+        assert folder_paths.is_dangerous_content_type(ct) is False, ct
+    # None / empty (mimetypes.guess_type miss) must not be treated as dangerous.
+    assert folder_paths.is_dangerous_content_type(None) is False
+    assert folder_paths.is_dangerous_content_type('') is False