What’s Vulnerable › Vulnerabilities

CVE-2026-96260: Mattermost server missing request body size limit on plugin routes allows denial of service by an authenticated user

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-22 · updated 2026-10-07
• Weakness: CWE-789

Description

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to enforce a request body size limit during CSRF validation of plugin requests which allows an authenticated user to exhaust server memory and cause a denial of service via a large request body sent to a plugin endpoint.. Mattermost Advisory ID: MMSA-2026-00775

Affected products

• Mattermost: from 11.7.0 before 11.7.11; from 11.8.0 before 11.8.6; from 11.9.0 before 11.9.2; from 11.10.0 before 11.10.2 — fixed in 11.10.2, 11.7.11, 11.8.6, 11.9.2

How to fix

Upgrade to a fixed version: Mattermost 11.10.2, 11.7.11, 11.8.6, 11.9.2. Check the vendor advisory for mitigations.

References

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

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