CVE-2026-21388

LOW

Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}} Webhook Endpoint

Title source: cna

Description

Mattermost Plugins versions <=2.3.1 fail to limit the request body size on the {{/lifecycle}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610

References (1)

[Vendor Advisory] https://mattermost.com/security-updates

Scores

CVSS v3 3.7

EPSS 0.0005

EPSS Percentile 14.3%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Details

CWE

CWE-770

Status published

Products (3)

Mattermost/Mattermost < 2.3.1

mattermost/mattermost < 2.3.2.0

Mattermost/Mattermost 2.3.2.0

Published Apr 09, 2026

Tracked Since Apr 09, 2026