CVE-2025-11776Network attack vector

Archived-channel discovery via guest authorization bypass

Published Nov 14, 2025 · Updated Nov 14, 2025

Incorrect authorization in Mattermost before 11.0.0 allows remote authenticated users with guest access to discover archived public channels. The archived-channel search endpoint returns matching public channels without enforcing the guest role's channel-visibility restriction. A guest account and team identifier are required; exposure is limited to channel discovery, with no reported access to channel contents.

CVSS severity4.3
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Mattermost before 11.0.0 allows remote authenticated users with guest access to discover archived public channels. The archived-channel search endpoint returns matching public channels without enforcing the guest role's channel-visibility restriction. A guest account and team identifier are required; exposure is limited to channel discovery, with no reported access to channel contents.

The record

CVE
CVE-2025-11776
Published
Nov 14, 2025
Updated
Nov 14, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-863, T1213.005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 14, 2025Record 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=<11 <=<11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=<11 <=<11

Published CVSS scores

4.3Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1213.005Data from Information Repositories: Messaging Applications

Public exploit references

No public exploit references are available in this record.

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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