CVE-2026-42276 — Onyx is an open-source AI platform. Prior to versions
CVE-2026-42276 — Onyx is an open-source AI platform. Prior to versions 3.0.9, 3.1.6, and 3.2.6, the POST /chat/stop-chat-session/{chat_session_id} endpoint lets any authenticated user stop any other user's active chat session. The endpoint checks authentication but never verifies the session belongs
What This Means For You
- If your environment is affected by CWE-639, review your exposure and prioritize patching based on your environment. Monitor vendor advisories for CVE-2026-42276 updates and patches.
Related ATT&CK Techniques
🛡️ Detection Rules
2 rules · 6 SIEM formats2 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-42276 - Onyx Chat Session Termination
title: CVE-2026-42276 - Onyx Chat Session Termination
id: scw-2026-05-08-ai-1
status: experimental
level: medium
description: |
Detects the specific API endpoint used in CVE-2026-42276 where an authenticated user can stop another user's active chat session by sending a POST request to /chat/stop-chat-session/{chat_session_id}. This rule specifically targets the vulnerable endpoint without verifying session ownership.
author: SCW Feed Engine (AI-generated)
date: 2026-05-08
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-42276/
tags:
- attack.impact
- attack.t1531
logsource:
category: webserver
detection:
selection:
cs-method:
- 'POST'
cs-uri:
- '/chat/stop-chat-session/*'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-42276 | vulnerability | CVE-2026-42276 |
| CWE-639 | weakness | CWE-639 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 08, 2026 at 08:16 UTC |
This content was curated and summarized by Shimi's Cyber World for informational purposes. It is not copied or republished in full. All intellectual property rights remain with the original author and source.
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