Session Manipulation Vulnerability in Onyx Open-source AI Platform
CVE-2026-42276

4.3MEDIUM

Key Information:

Vendor

Onyx-dot-app

Status
Onyx
Vendor
CVE Published:
8 May 2026

What is CVE-2026-42276?

The Onyx AI platform has a vulnerability that allows authenticated users to inadvertently terminate other users' chat sessions using the shared POST /chat/stop-chat-session/{chat_session_id} endpoint. While the endpoint performs authentication checks, it fails to validate if the chat session belongs to the user attempting the action. This oversight permits knowledgeable attackers to disrupt ongoing chat sessions of other users by leveraging their session UUIDs, which poses a significant risk to user experience and data integrity.

Affected Version(s)

onyx < 3.0.9 < 3.0.9

onyx >= 3.1.0, < 3.1.6 < 3.1.0, 3.1.6

onyx >= 3.2.0, < 3.2.6 < 3.2.0, 3.2.6

References

https://github.com/onyx-dot-app/onyx/security/advisories/...
x_refsource_CONFIRM

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.