CVE-2026-5308: Missing request body size limits on Zoom plugin HTTP endpoints

Q: What is the severity of CVE-2026-5308?

The severity of CVE-2026-5308 is medium with a score of 4.9.

Q: 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.

Q: What does CVE-2026-5308 describe?

CVE-2026-5308 describes missing request body size limits on Zoom plugin HTTP endpoints in certain Mattermost versions.

Q: 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.

Published May 22, 2026

Updated

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

1 affected component

Mattermost Mattermost=11.6.0, >=11.5.0<=11.5.3, >=11.4.0<=11.4.4, >=10.11.0<=10.11.14

Remediation

Information

Update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, 10.11.15 or higher.

Event History

May 22, 2026

CVE Published

via MITRE·10:20 AM

Data Sourced

via MITRE·10:20 AM

RemedyDescriptionSeverityWeakness

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.

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