Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-87994

CVE-2026-87994MEDIUM

open-webui open-webui — Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   L   N  U  N  L  N    4.3   .0037   28.8     —

AFFECTED
  Product     Versions              Fixed
  open-webui  >= 0.9.5, < 0.11.1 –  —

TIMELINE
  Sep 9   Reserved by GitHub_M
  Sep 9   Published (CNA: GitHub_M)
  Sep 16  EXPLOIT PUBLISHED — CVE-2026-87994 (open-webui). Public exploit reference added.

CWE-639, CWE-862 · CNA: GitHub_M · CVSS v3.1 · 4 references · NVD status: Analyzed

Description

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
September 9, 2026	Reserved	Reserved by GitHub_M
September 9, 2026	Published	Published (CNA: GitHub_M)
September 16, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-87994 (open-webui). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
open-webui	open-webui	—	>= 0.9.5, < 0.11.1	—

Weaknesses

CWE-639 · CWE-862

References (4)

https://github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc [Patch]
https://github.com/open-webui/open-webui/pull/28631 [Issue Tracking, Patch]
https://github.com/open-webui/open-webui/releases/tag/v0.11.1 [Release Notes]
https://github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-87994 at cve.org

Vendors: open-webui

Weaknesses: CWE-639 · CWE-862

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-87994 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.