GHSA-gfm2-xm6c-37qc is a high-severity (CVSS 7.1) CWE-639 vulnerability in open-webui. O3 Security confirms whether GHSA-gfm2-xm6c-37qc is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Open WebUI has Broken Access Control for Completions API
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-gfm2-xm6c-37qc.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-gfm2-xm6c-37qc plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 358,265 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
open-webuiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Any user X can continue the conversation of any other user Y, as long as the Chat ID of Y is known. User X does not even need to be an admin to do so.
Details
A user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user. OWUI does not check to match the Chat ID with the user that created that Chat ID. Note that both users will need access to the same model. This is especially relevant if there is a shared pipeline model between users.
PoC
- Using OWUI v0.6.18
- Sign in with any user
X - Generate an API Key for user
Xusing the settings - Create another user
Y, and have a conversation in OWUI. Copy the Chat ID from the URL. - User
Xcan now use the API/api/chat/completionsand the Chat ID from step 4 to continue the conversation of userY
Impact
Large impact to any user in OWUI. People can read your conversations, and access private information if they know your Chat ID (which is in the URL of the chat).
Resolution
Fixed in commit cf4218e68, first released in v0.9.0 (Apr 2026). The chat_completion handler at backend/open_webui/main.py:1868 now explicitly verifies chat ownership via Chats.is_chat_owner(chat_id, user.id) for any request that targets an existing chat, and raises 404 for non-owners (admin bypass preserved per the documented threat model). New chats (no chat_id supplied, or freshly inserted via the is_new_chat branch) are unaffected. Users on >= 0.9.0 are not affected.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | open-webui | all versions | 0.9.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-webui. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update open-webui to 0.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gfm2-xm6c-37qc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-gfm2-xm6c-37qc is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-gfm2-xm6c-37qc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-gfm2-xm6c-37qc in your dependencies?
O3 detects GHSA-gfm2-xm6c-37qc across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.