CVE-2026-42276: CWE-639: Authorization Bypass Through User-Controlled Key in onyx-dot-app onyx
CVE-2026-42276 is an authorization bypass vulnerability in the onyx open-source AI platform affecting versions prior to 3.0.9, 3.1.6, and 3.2.6. The POST /chat/stop-chat-session/{chat_session_id} endpoint allows any authenticated user to stop another user's active chat session without verifying ownership of the session. This enables an attacker who knows a chat session UUID to interrupt another user's LLM generation mid-stream. The vulnerability has been patched in versions 3.
AI Analysis
Technical Summary
Onyx versions before 3.0.9, 3.1.6, and 3.2.6 contain an authorization bypass (CWE-639) in the POST /chat/stop-chat-session/{chat_session_id} endpoint. While the endpoint requires authentication, it does not verify that the chat session being stopped belongs to the authenticated user. This allows any authenticated user who knows a valid chat session UUID to forcibly stop another user's active chat session, disrupting their LLM generation process. The issue has been addressed by patches in the specified versions.
Potential Impact
The vulnerability allows an authenticated user to disrupt the availability of other users' chat sessions by stopping their active LLM generation mid-stream. There is no confidentiality or integrity impact reported. The impact is limited to denial of service against chat sessions.
Mitigation Recommendations
This vulnerability has been patched in onyx versions 3.0.9, 3.1.6, and 3.2.6. Users should upgrade to one of these versions or later to remediate the issue. No other mitigation guidance is provided or necessary as the fix is available.
CVE-2026-42276: CWE-639: Authorization Bypass Through User-Controlled Key in onyx-dot-app onyx
Description
CVE-2026-42276 is an authorization bypass vulnerability in the onyx open-source AI platform affecting versions prior to 3.0.9, 3.1.6, and 3.2.6. The POST /chat/stop-chat-session/{chat_session_id} endpoint allows any authenticated user to stop another user's active chat session without verifying ownership of the session. This enables an attacker who knows a chat session UUID to interrupt another user's LLM generation mid-stream. The vulnerability has been patched in versions 3.
CVSS v3.1
Score 4.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Onyx versions before 3.0.9, 3.1.6, and 3.2.6 contain an authorization bypass (CWE-639) in the POST /chat/stop-chat-session/{chat_session_id} endpoint. While the endpoint requires authentication, it does not verify that the chat session being stopped belongs to the authenticated user. This allows any authenticated user who knows a valid chat session UUID to forcibly stop another user's active chat session, disrupting their LLM generation process. The issue has been addressed by patches in the specified versions.
Potential Impact
The vulnerability allows an authenticated user to disrupt the availability of other users' chat sessions by stopping their active LLM generation mid-stream. There is no confidentiality or integrity impact reported. The impact is limited to denial of service against chat sessions.
Mitigation Recommendations
This vulnerability has been patched in onyx versions 3.0.9, 3.1.6, and 3.2.6. Users should upgrade to one of these versions or later to remediate the issue. No other mitigation guidance is provided or necessary as the fix is available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-26T11:53:27.708Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69fd6bcccbff5d861092328b
Added to database: 05/08/2026, 04:51:24 UTC
Last enriched: 05/15/2026, 11:01:16 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 119
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