CVE-2026-42276

MEDIUMNVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 80% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
4.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
4.3
EG Score
4.3(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity43% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
20.1%
KEV
Not listed

Published

May 8, 2026

Last Modified

May 12, 2026

Advisory Details (1)

Auto-updated May 8, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

IDOR in /chat/stop-chat-session allows any authenticated user to interrupt other users chat sessions · Advisory · onyx-dot-app/onyx · GitHub

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

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 33× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:17 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:11 UTCEG score recompute
  4. 2026-07-22 14:08 UTCEPSS rescore
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  10. 2026-07-16 17:03 UTCEPSS rescore
  11. 2026-07-16 06:19 UTCOSV refresh
  12. 2026-07-15 16:57 UTCEPSS rescore
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  1. 2026-07-01 15:06 UTCEPSS rescore
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  5. 2026-06-28 04:56 UTCEPSS rescore
  6. 2026-06-27 03:08 UTCEPSS rescore
  7. 2026-06-25 13:49 UTCEPSS rescore
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  9. 2026-06-24 14:05 UTCEPSS rescore
  10. 2026-06-23 21:33 UTCEPSS rescore
  11. 2026-06-22 14:25 UTCEPSS rescore
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  13. 2026-06-21 14:56 UTCEPSS rescore
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  15. 2026-06-21 01:59 UTCEPSS rescore
  16. 2026-06-19 19:25 UTCEPSS rescore
  17. 2026-06-18 17:52 UTCEPSS rescore
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  19. 2026-06-17 17:53 UTCEPSS rescore
  20. 2026-06-16 17:52 UTCEPSS rescore
  21. 2026-06-15 17:49 UTCEPSS rescore
  22. 2026-06-13 23:00 UTCEPSS rescore
  23. 2026-06-12 23:12 UTCEPSS rescore
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  25. 2026-06-11 14:00 UTCEPSS rescore
  26. 2026-06-10 22:18 UTCEPSS rescore
  27. 2026-06-10 13:22 UTCEPSS rescore
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  29. 2026-06-08 14:17 UTCEPSS rescore
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  31. 2026-06-07 15:25 UTCEPSS rescore
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  33. 2026-06-06 13:47 UTCEPSS rescore
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  35. 2026-06-05 22:47 UTCEPSS rescore
  36. 2026-06-05 06:10 UTCEPSS rescore
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  40. 2026-06-02 20:13 UTCEPSS rescore
  41. 2026-06-01 13:52 UTCEPSS rescore
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  43. 2026-05-31 22:30 UTCEPSS rescore
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  45. 2026-05-31 00:16 UTCEPSS rescore
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  47. 2026-05-29 13:44 UTCEPSS rescore
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  49. 2026-05-28 13:44 UTCEPSS rescore
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  51. 2026-05-28 13:44 UTCEPSS rescore
  52. 2026-05-27 13:40 UTCEPSS rescore
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  55. 2026-05-26 13:44 UTCEPSS rescore
  56. 2026-05-26 07:18 UTCEPSS rescore
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  58. 2026-05-20 22:38 UTCEPSS rescore
  59. 2026-05-20 22:38 UTCEPSS rescore
  60. 2026-05-20 13:48 UTCEG score recompute
  61. 2026-05-20 11:22 UTCEPSS rescore
  62. 2026-05-20 11:22 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-42276?
CVE-2026-42276 is a medium vulnerability published on May 8, 2026. 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/{chatsessionid} 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…
When was CVE-2026-42276 disclosed?
CVE-2026-42276 was first published in the National Vulnerability Database on May 8, 2026, with the most recent update on May 12, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42276 actively exploited?
CVE-2026-42276 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 20.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42276?
CVE-2026-42276 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-42276?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42276, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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