CVE-2026-2456

Denial of Service via Unbounded Memory Allocation in Integration Actions

Published Mar 16, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
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

Remediation

Vendor Solution

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

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-34g8-9fpp-46ch Mattermost fails to limit the size of responses from integration action endpoints
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost
Mattermost server
Vendors & Products Mattermost mattermost
Mattermost server
Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost
Mattermost mattermost Server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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
Title Denial of Service via Unbounded Memory Allocation in Integration Actions
Weaknesses CWE-789
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Mar 16, 2026, 1:49 PM
Reserved
Feb 13, 2026, 11:02 AM
Status
Analyzed
Published
Mar 16, 2026, 2:19 PM
Modified
Jun 17, 2026, 10:30 AM