# CVE-2026-87994 — open-webui

> As of 2026-09-10, CVE-2026-87994 is a MEDIUM-severity vulnerability in open-webui, CVSS v3.1 4.3, EPSS 0.2% (11.6th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-87994 as of 2026-09-10; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-10

## What is CVE-2026-87994?

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.

The record classifies CVE-2026-87994 under weakness classes [CWE-639](https://intel.threadlinqs.com/cwe/CWE-639), [CWE-862](https://intel.threadlinqs.com/cwe/CWE-862). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 26 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 4.3 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 11.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 2.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-09, last modified 2026-09-10

## Is CVE-2026-87994 being exploited?

It currently carries a trending score of 32 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [open-webui](https://intel.threadlinqs.com/vendors/open-webui): open-webui

## How to fix CVE-2026-87994

No vendor patch reference has been recorded for CVE-2026-87994 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-87994

No threat campaign in the Threadlinqs corpus currently references CVE-2026-87994, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-09-11. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

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

**Other references**

- [github.com](https://github.com/open-webui/open-webui/pull/28631)
- [github.com (7d392bedc9c1aaecc94509a58e59186b614433dc)](https://github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc)
- [github.com (v0.11)](https://github.com/open-webui/open-webui/releases/tag/v0.11.1)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-87994
Full detection coverage and IOCs for threats exploiting CVE-2026-87994 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp