Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622

Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

Update Mattermost to versions 11.6.0, 11.5.2, 10.11.14 or higher.


Workaround

No workaround given by the vendor.

References
History

Mon, 18 May 2026 08:00:00 +0000

Type Values Removed Values Added
Description Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622
Title Unescaped variables during error page composition
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 3.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-05-18T06:58:29.673Z

Reserved: 2026-03-03T17:33:56.666Z

Link: CVE-2026-3495

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-18T08:16:13.900

Modified: 2026-05-18T08:16:13.900

Link: CVE-2026-3495

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-18T09:30:22Z

Weaknesses