What’s Vulnerable › Vulnerabilities

CVE-2025-55074: Channel member objects leak read status

• Severity: low (CVSS 3.5 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: 2025-11-18 · updated 2026-10-19
• Weakness: CWE-1426

Description

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to enforce access permissions on the Agents plugin which allows other users to determine when users had read channels via channel member objects

Affected products

• Mattermost: from 10.5.0 before 10.5.12; from 10.11.0 before 10.11.4 — fixed in 10.11.4, 10.5.12

How to fix

Upgrade to a fixed version: Mattermost 10.11.4, 10.5.12. Check the vendor advisory for mitigations.

References

• https://mattermost.com/security-updates

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