CVE-2026-2456 PUBLISHED

Denial of Service via Unbounded Memory Allocation in Integration Actions

Assigner: Mattermost
Reserved: 13.02.2026 Published: 16.03.2026 Updated: 16.03.2026

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS Score: 5.3

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	Required	Availability Impact	High

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.3.0 to 11.3.0 (incl.) affected from 11.2.0 to 11.2.2 (incl.) affected from 10.11.0 to 10.11.10 (incl.) Version 11.4.0 is unaffected Version 11.3.1 is unaffected Version 11.2.3 is unaffected Version 10.11.11 is unaffected

Solutions

Update Mattermost to versions 11.4.0, 11.3.1, 11.2.3, 10.11.11 or higher.

Credits

Daniel Espino Garcia finder

References

MMSA-2026-00571

Problem Types

CWE-789: Memory Allocation with Excessive Size Value CWE