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TI-2026-30587 Aliases CVE-2026-42276

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

Priority MEDIUM 53CWE-639Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · None · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-639.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00279 20th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed onyx (onyx-dot-app): 3.0.9, 3.1.6, 3.2.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
onyx-dot-apponyxbefore 3.0.9; 3.1.0 to before 3.1.6; 3.2.0 to before 3.2.63.0.9, 3.1.6, 3.2.6Patch availableCNA
  • onyx Vendoronyx-dot-app Affected before 3.0.9; 3.1.0 to before 3.1.6; 3.2.0 to before 3.2.6 Fixed in 3.0.9, 3.1.6, 3.2.6 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:onyx:onyx:*:*:*:*:*:*:*:*before 3.0.9; 3.1.0 to before 3.1.6; 3.2.0 to before 3.2.6VulnerableOnyx
  • cpe:2.3:a:onyx:onyx:*:*:*:*:*:*:*:* Versions before 3.0.9; 3.1.0 to before 3.1.6; 3.2.0 to before 3.2.6 Vulnerable ·Onyx

Remediation

  • Fix · CNA onyx (onyx-dot-app) Fixed in 3.0.9, 3.1.6, 3.2.6

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-42276

References

Exploit 1

  • TI-2026-58811 Onyx 4.6.6 Custom Tool Secret Header Disclosure via Tool Endpoints CVSS 4.0HIGH 7.1
  • TI-2026-45084 Authorization bypass in onyx-dot-app onyx CVSS 3.1MEDIUM 6.5
  • TI-2026-50048 Onyx: Cross-user OAuth-token leak via /api/mcp/servers* for per-user MCP servers CVSS 3.1CRITICAL 9.6
  • TI-2026-80125 Cross-site scripting in onyx-dot-app Onyx PreviewTab.tsx CVSS 4.0MEDIUM 5.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences