CVE-2026-87994

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 88% 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, secondary
Elevated
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: Elevated riskExposed: 0

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

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.5 until 0.11.1, the channel branch of chat_completion in backend/open_webui/main.py checked channel write access and channel membership for a supplied message_id but did not verify that the calling user authored the targeted message. A channel member could use the chat completions endpoint to replace another member's message while preserving the victim as the stored author, altering the conversation record without gaining access to other channels. This issue is fixed in version 0.11.1.

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 PROB
0%
EPSS %ILE
12%
KEV
Not listed

Published

September 9, 2026

Last Modified

September 16, 2026

Advisory Details (4)

Auto-updated Sep 9, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github_commit, github_release, github.
github_release Patch Available

v0.11.1

Patch available: open-webui/open-webui v0.11.1

https://github.com/open-webui/open-webui/releases/tag/v0.11.1
github_commit

commit 7d392bedc9c1 (open-webui/open-webui)

Fix landed in open-webui/open-webui commit 7d392bedc9c1 — awaiting tagged release

https://github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc
github_pr

refac: align the channel completion gate with the message update route

Fix merged in open-webui/open-webui PR #28631 on 2026-08-17 — awaiting tagged release

https://github.com/open-webui/open-webui/pull/28631
github Patch Available🟡 PoC Available

Channel members can overwrite another member's message via the chat completions endpoint · Advisory · open-webui/open-webui · GitHub

Affected: 0.11.1 by commit

https://github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8

Vendor Advisories for CVE-2026-87994(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
open-webui0.10.0 ... 0.9.6 (6 versions)0.11.1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 21× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 14:16 UTCEG score recompute
  3. 2026-09-17 19:32 UTCEPSS rescore
  4. 2026-09-16 15:30 UTCEG score recompute
  5. 2026-09-16 14:09 UTCEPSS rescore
  6. 2026-09-16 12:41 UTCEG score recompute
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 13:18 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-14 13:55 UTCEG score recompute
  11. 2026-09-13 16:48 UTCEPSS rescore
  12. 2026-09-12 15:09 UTCEG score recompute
  13. 2026-09-12 15:02 UTCEPSS rescore
  14. 2026-09-11 15:46 UTCEG score recompute
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-11 14:53 UTCEPSS rescore
  17. 2026-09-10 16:22 UTCEG score recompute
  18. 2026-09-10 16:10 UTCEG score recompute
  19. 2026-09-09 22:31 UTCEG score recompute
  20. 2026-09-09 21:31 UTCEG score recompute
  21. 2026-09-09 21:30 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-87994?
CVE-2026-87994 is a medium vulnerability published on September 9, 2026. Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.5 until 0.11.1, the channel branch of chatcompletion in backend/openwebui/main.py checked channel write access and channel membership for a supplied message_id but did not verify that the calling user…
When was CVE-2026-87994 disclosed?
CVE-2026-87994 was first published in the National Vulnerability Database on September 9, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-87994 actively exploited?
CVE-2026-87994 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 87.6% of all scored CVEs.
What is the CVSS score of CVE-2026-87994?
CVE-2026-87994 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-87994?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-87994, 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.

Dependency Blast Radius

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