CVE-2026-1629: Permalink Preview Information Disclosure After Permission Revocation

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-16 · updated 2026-06-17
Weakness: CWE-672

Description

Mattermost versions 10.11.x <= 10.11.10 Fail to invalidate cached permalink preview data when a user loses channel access which allows the user to continue viewing private channel content via previously cached permalink previews until cache reset or relogin.. Mattermost Advisory ID: MMSA-2026-00580

Affected products

Mattermost: from 10.11.0 before 10.11.11 — fixed in 10.11.11

How to fix

Upgrade to a fixed version: Mattermost 10.11.11. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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