Summary
The profile_image_url field on the user profile update form accepted arbitrary data: URI values without MIME-type validation. Two distinct attack paths were independently demonstrated by separate reporters:
-
data:text/html;base64,... in a new browser tab (raresvis, 2025-04-17) — when a victim right-clicks a user's profile picture and chooses "Open image in new tab", the browser navigates to the data: URL and executes embedded scripts in the data: origin. Limited to social-engineering / redirect attacks because the script does not run in the application origin.
-
data:image/svg+xml;base64,... re-served by the application origin (Gh05t666nero, 2026-01-09) — GET /api/v1/users/{user_id}/profile/image decoded the base64 and returned StreamingResponse(media_type=<user-controlled>) extracted from the data: header. With media_type=image/svg+xml and Content-Disposition: inline, the SVG-embedded scripts executed in the application origin, enabling JWT theft from localStorage and full account takeover of any user — including admins — who loaded the malicious profile image URL.
Both attack paths share the same root cause (lack of MIME-type validation on profile_image_url) and are closed by the same fix.
Vulnerable code (v0.7.0)
backend/open_webui/routers/users.py get_user_profile_image_by_id():
elif user.profile_image_url.startswith("data:image"):
header, base64_data = user.profile_image_url.split(",", 1)
image_data = base64.b64decode(base64_data)
image_buffer = io.BytesIO(image_data)
media_type = header.split(";")[0].lstrip("data:") # user-controlled
return StreamingResponse(
image_buffer,
media_type=media_type,
headers={"Content-Disposition": "inline"},
)Fix
Commit 773787c74 (2026-02-11), first contained in tag v0.8.0, applies the validate_profile_image_url field validator to every form that accepts profile_image_url (UserModel, UpdateProfileForm, SignupForm in backend/open_webui/models/users.py and backend/open_webui/models/auths.py). The validator explicitly rejects data:image/svg+xml and any non-image data URI, allowing only data:image/{png,jpeg,gif,webp};base64 plus known internal paths and http(s):// URLs. This blocks both attack vectors at form submission time, so a malicious URL can no longer be persisted to the database.
Credits
- raresvis — discovered the
data:text/html-via-new-tab path
- Gh05t666nero — discovered the
data:image/svg+xml-via-server-side path (the more severe origin-XSS vector that determined the consolidated CVSS)
Per our Report Handling policy, the cluster is consolidated into the earliest filing with credit to every reporter who demonstrated a distinct exploitation path.
Affected / patched versions
- Affected:
< 0.8.0
- Patched:
>= 0.8.0
References
raresvis Reporter
Gh05t666nero Reporter
Classic298 Coordinator
Summary
The
profile_image_urlfield on the user profile update form accepted arbitrarydata:URI values without MIME-type validation. Two distinct attack paths were independently demonstrated by separate reporters:data:text/html;base64,...in a new browser tab (raresvis, 2025-04-17) — when a victim right-clicks a user's profile picture and chooses "Open image in new tab", the browser navigates to the data: URL and executes embedded scripts in thedata:origin. Limited to social-engineering / redirect attacks because the script does not run in the application origin.data:image/svg+xml;base64,...re-served by the application origin (Gh05t666nero, 2026-01-09) —GET /api/v1/users/{user_id}/profile/imagedecoded the base64 and returnedStreamingResponse(media_type=<user-controlled>)extracted from thedata:header. Withmedia_type=image/svg+xmlandContent-Disposition: inline, the SVG-embedded scripts executed in the application origin, enabling JWT theft fromlocalStorageand full account takeover of any user — including admins — who loaded the malicious profile image URL.Both attack paths share the same root cause (lack of MIME-type validation on
profile_image_url) and are closed by the same fix.Vulnerable code (v0.7.0)
backend/open_webui/routers/users.pyget_user_profile_image_by_id():Fix
Commit
773787c74(2026-02-11), first contained in tag v0.8.0, applies thevalidate_profile_image_urlfield validator to every form that acceptsprofile_image_url(UserModel,UpdateProfileForm,SignupForminbackend/open_webui/models/users.pyandbackend/open_webui/models/auths.py). The validator explicitly rejectsdata:image/svg+xmland any non-image data URI, allowing onlydata:image/{png,jpeg,gif,webp};base64plus known internal paths andhttp(s)://URLs. This blocks both attack vectors at form submission time, so a malicious URL can no longer be persisted to the database.Credits
data:text/html-via-new-tab pathdata:image/svg+xml-via-server-side path (the more severe origin-XSS vector that determined the consolidated CVSS)Per our Report Handling policy, the cluster is consolidated into the earliest filing with credit to every reporter who demonstrated a distinct exploitation path.
Affected / patched versions
< 0.8.0>= 0.8.0References