Mattermost Vulnerability in Integration Action Endpoints
CVE-2026-2456

5.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
16 March 2026

What is CVE-2026-2456?

The Mattermost application fails to restrict the size of responses from integration action endpoints, potentially allowing an authenticated attacker to exploit this weakness. By triggering an interaction through a malicious integration server that returns excessively large responses when a user activates an interactive message button, the attacker can lead to server memory exhaustion, resulting in denial of service for legitimate users. This poses a significant risk to service availability and overall platform performance.

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Affected Version(s)

Mattermost 11.3.0

Mattermost 11.2.0 <= 11.2.2

Mattermost 10.11.0 <= 10.11.10

References

https://mattermost.com/security-updates
vendor-advisory

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Daniel Espino Garcia
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