CVE-2026-87994Public exploitNetwork attack vector

Message tampering via missing authorship check

Published Sep 9, 2026 · Updated Sep 10, 2026

Missing authorization in Open WebUI 0.9.5 through 0.11.0 allows remote authenticated users to overwrite another channel member's message. The channel branch of chat_completion accepts a supplied message_id after checking channel membership and write access but never verifies that the caller authored the targeted message. Channels must be enabled, and the caller must be an approved member with channel write access; the altered text remains stored under the victim's identity.

CVSS severity4.3
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Open WebUI 0.9.5 through 0.11.0 allows remote authenticated users to overwrite another channel member's message. The channel branch of chat_completion accepts a supplied message_id after checking channel membership and write access but never verifies that the caller authored the targeted message. Channels must be enabled, and the caller must be an approved member with channel write access; the altered text remains stored under the victim's identity.

The record

CVE
CVE-2026-87994
Published
Sep 9, 2026
Updated
Sep 10, 2026
Vendor
Open WebUI
Product
Open WebUI
Classifications
CWE-639, CWE-862, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.9.5, < 0.11.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Open WebUI · Open WebUIversion=>= 0.9.5, < 0.11.1

Published CVSS scores

4.3GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
CWE-862Missing Authorization
T1565.001Stored Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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