CVE-2026-4646: Insufficient input validation in GitHub plugin API causes denial of service

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 validate user-supplied input in API request handlers which allows an authenticated attacker to crash the plugin process via a crafted HTTP request to the PR details endpoint.. Mattermost Advisory ID: MMSA-2026-00638

Affected Software

1 affected component
Mattermost Mattermost<=11.6.0, <=11.5.3, <=11.4.4, <=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·10:25 AM
Data Sourced
via MITRE·10:25 AM
RemedyDescriptionSeverityWeakness
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Frequently Asked Questions

1

What is the severity of CVE-2026-4646?

The severity of CVE-2026-4646 is medium with a score of 4.3.

2

What is CVE-2026-4646?

CVE-2026-4646 is a vulnerability in Mattermost that allows authenticated attackers to crash the plugin process due to insufficient input validation.

3

How do I fix CVE-2026-4646?

To fix CVE-2026-4646, update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, 10.11.15 or higher.

4

What versions of Mattermost are affected by CVE-2026-4646?

Mattermost versions 11.6.x up to 11.6.0, 11.5.x up to 11.5.3, 11.4.x up to 11.4.4, and 10.11.x up to 10.11.14 are affected by CVE-2026-4646.

5

What type of attack is enabled by CVE-2026-4646?

CVE-2026-4646 enables a denial of service attack via crafted HTTP requests to the PR details endpoint.

Company

Resources

Contact

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