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4.3

Mattermost <11: Guest users can see archived public channels

CVE-2025-11776 · published 11 months ago
Summary

Guest users on Mattermost servers with versions less than 11 can find archived public channels they shouldn't be able to access. This is a security concern because it could allow unauthorized access to sensitive information. Update to Mattermost version 11 or later to fix this issue.

What to do
  • Update github.com mattermost to version 8.0.0-20250815165020-c8d66301415d.
  • Update github.com mattermost to version 5.3.2-0.20250815165020-c8d66301415d.
  • Update mattermost mattermost_server to version 11.0.0 or later.
Affected software
Ecosystem VendorProductAffected versions
go github.com mattermost < 8.0.0-20250815165020-c8d66301415d
Fix: upgrade to 8.0.0-20250815165020-c8d66301415d
go github.com mattermost < 5.3.2-0.20250815165020-c8d66301415d
Fix: upgrade to 5.3.2-0.20250815165020-c8d66301415d
go github.com mattermost < 5.3.2-0.20250815165020-c8d66301415d
Fix: upgrade to 5.3.2-0.20250815165020-c8d66301415d
go github.com mattermost < 5.3.2-0.20250815165020-c8d66301415d
Fix: upgrade to 5.3.2-0.20250815165020-c8d66301415d
go github.com mattermost < 5.3.2-0.20250815165020-c8d66301415d
Fix: upgrade to 5.3.2-0.20250815165020-c8d66301415d
– mattermost mattermost_server < 11.0.0
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Original advisory text
Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the `/api/v4/teams/{team_id}/channels/searc...
Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the `/api/v4/teams/{team_id}/channels/search_archived` endpoint
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
4.3 Medium
Exploitation
<1% chance of attack within 30 days
Type
CWE-863Incorrect Authorization
Timeline
Published14 Nov 2025
Updated29 Oct 2026
First seen6 Mar 2026
Sources
GHSA-j6gg-r5jc-47cm · GHSA
CVE-2025-11776 · NVD
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