CVE-2026-3116: Improper Input Validation in Zoom Plugin Webhook Handler

Severity: medium (CVSS 4.9 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: 2026-03-26 · updated 2026-06-17
Weakness: CWE-400

Description

Mattermost Plugins versions <=11.4 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to validate incoming request size which allows an authenticated attacker to cause service disruption via the webhook endpoint. Mattermost Advisory ID: MMSA-2026-00589

Affected products

Mattermost: from 10.11.0 before 10.11.12; from 11.2.0 before 11.2.4; from 11.3.0 before 11.3.2; from 11.4.0 before 11.4.1 — fixed in 10.11.12, 11.2.4, 11.3.2, 11.4.1

How to fix

Upgrade to a fixed version: Mattermost 10.11.12, 11.2.4, 11.3.2, 11.4.1. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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