Medium severity · published May 8, 2026
CVE-2026-42276
Onyx: IDOR in /chat/stop-chat-session allows any authenticated user to interrupt other users chat sessions
4.3
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 20% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ON
onyx · onyx-dot-app
< 3.0.9; >= 3.1.0, < 3.1.6; >= 3.2.0, < 3.2.6 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42276
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42276
Exploit
https://github.com/onyx-dot-app/onyx/security/advisories/GHSA-rw6w-hp62-gc8w
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