CVE-2026-42276

MEDIUM

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

Title source: cna
STIX 2.1

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.

References (1)

Core 1
Core References

Scores

CVSS v3 4.3
EPSS 0.0005
EPSS Percentile 14.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-639
Status published
Products (4)
onyx/onyx < 3.0.9
onyx-dot-app/onyx < 3.0.9
onyx-dot-app/onyx >= 3.1.0, < 3.1.6
onyx-dot-app/onyx >= 3.2.0, < 3.2.6
Published May 08, 2026
Tracked Since May 08, 2026