CVE-2026-21388: Mattermost MS Teams plugin doesn't limit the request body size on the /lifecycle webhook endpoint
(updated )
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
- github.com/advisories/GHSA-x274-8qfc-hrgf
- github.com/mattermost/mattermost-plugin-msteams
- github.com/mattermost/mattermost-plugin-msteams/commit/6fe4d295592ecc8767d67e69286cbeec01be3210
- github.com/mattermost/mattermost-plugin-msteams/releases/tag/v2.3.2
- mattermost.com/security-updates
- nvd.nist.gov/vuln/detail/CVE-2026-21388
Code Behaviors & Features
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