Vulnerability · Published May 8, 2026 · Assigned by GitHub_M

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

Medium 4.3

In plain English

A medium-severity authorization bypass via user-controlled key in onyx from onyx-dot-app. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 20% of all known vulnerabilities).

Severity (CVSS 3.1)4.3Medium

Exploit odds (30 days)0.3%top 79.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
onyx-dot-app	onyx	< 3.0.9>= 3.1.0, < 3.1.6>= 3.2.0, < 3.2.6

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

References

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