CVE-2026-5308: Missing request body size limits on Zoom plugin HTTP endpoints
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to enforce request body size limits on plugin HTTP endpoints which allows an attacker to cause a denial of service via crafted oversized HTTP requests.. Mattermost Advisory ID: MMSA-2026-00646
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.7.0 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.6.1 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.5.4 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.4.5 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 10.11.15 - Compensating control
Mitigate denial-of-service risk by limiting/request-filtering HTTP request body sizes to what is expected for Mattermost plugin HTTP endpoints until Mattermost is upgraded to a fixed version (MMSA-2026-00646).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-5308?
The severity of CVE-2026-5308 is medium with a score of 4.9.
How do I fix CVE-2026-5308?
To fix CVE-2026-5308, update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, or 10.11.15 or higher.
What does CVE-2026-5308 describe?
CVE-2026-5308 describes missing request body size limits on Zoom plugin HTTP endpoints in certain Mattermost versions.
What is the impact of CVE-2026-5308?
The impact of CVE-2026-5308 allows an attacker to cause a denial of service via crafted oversized HTTP requests.
Which versions of Mattermost are affected by CVE-2026-5308?
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, and 10.11.x <= 10.11.14 are affected by CVE-2026-5308.