CVE-2026-42276: CWE-639: Authorization Bypass Through User-Controlled Key in onyx-dot-app onyx
Onyx versions prior to 3. 0. 9, 3. 1. 6, and 3. 2. 6 contain an authorization bypass vulnerability in the POST /chat/stop-chat-session/{chat_session_id} endpoint. Authenticated users can stop any other user's active chat session without verifying ownership of the session. This allows an attacker who knows a chat session UUID to interrupt another user's LLM generation mid-stream. The issue has been addressed in versions 3.
AI Analysis
Technical Summary
CVE-2026-42276 is an authorization bypass vulnerability in the onyx open-source AI platform. The affected endpoint, POST /chat/stop-chat-session/{chat_session_id}, authenticates the user but fails to verify that the chat session belongs to the caller. Consequently, any authenticated user can terminate other users' active chat sessions if they know the session UUID. This flaw affects onyx versions prior to 3.0.9, 3.1.6, and 3.2.6. The vulnerability is tracked under CWE-639 (Authorization Bypass Through User-Controlled Key) and has a CVSS 3.1 base score of 4.3 (medium severity).
Potential Impact
Exploitation allows an authenticated user to disrupt availability by terminating other users' active chat sessions, causing denial of service for those sessions. There is no impact on confidentiality or integrity reported. The attack requires knowledge of the target chat session UUID and authenticated access.
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 fixed versions or later to remediate the issue. Since this is not a cloud service, remediation depends on applying the vendor's fixed releases. Patch status is confirmed by the vendor advisory embedded in the description.
CVE-2026-42276: CWE-639: Authorization Bypass Through User-Controlled Key in onyx-dot-app onyx
Description
Onyx versions prior to 3. 0. 9, 3. 1. 6, and 3. 2. 6 contain an authorization bypass vulnerability in the POST /chat/stop-chat-session/{chat_session_id} endpoint. Authenticated users can stop any other user's active chat session without verifying ownership of the session. This allows an attacker who knows a chat session UUID to interrupt another user's LLM generation mid-stream. The issue has been addressed in versions 3.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-42276 is an authorization bypass vulnerability in the onyx open-source AI platform. The affected endpoint, POST /chat/stop-chat-session/{chat_session_id}, authenticates the user but fails to verify that the chat session belongs to the caller. Consequently, any authenticated user can terminate other users' active chat sessions if they know the session UUID. This flaw affects onyx versions prior to 3.0.9, 3.1.6, and 3.2.6. The vulnerability is tracked under CWE-639 (Authorization Bypass Through User-Controlled Key) and has a CVSS 3.1 base score of 4.3 (medium severity).
Potential Impact
Exploitation allows an authenticated user to disrupt availability by terminating other users' active chat sessions, causing denial of service for those sessions. There is no impact on confidentiality or integrity reported. The attack requires knowledge of the target chat session UUID and authenticated access.
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 fixed versions or later to remediate the issue. Since this is not a cloud service, remediation depends on applying the vendor's fixed releases. Patch status is confirmed by the vendor advisory embedded in the description.
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: 5/8/2026, 4:51:24 AM
Last enriched: 5/8/2026, 5:06:57 AM
Last updated: 5/8/2026, 11:56:52 AM
Views: 7
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