Description
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624
Published: 2026-04-15
Score: 6.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Unauthorized Access via Token Reuse
Action: Immediate Patch
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

Vendor Solution

Update Mattermost to versions 11.6.0, 10.11.13, 11.5.1, 11.4.3, 11.3.3 or higher.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-mh4x-rmrx-3hp4 Mattermost has session spoofing due to lack of single-use consumption of guest magic link tokens enforcement
References
History

Wed, 22 Apr 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server

Wed, 15 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 15 Apr 2026 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Wed, 15 Apr 2026 11:30:00 +0000

Type Values Removed Values Added
Description Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624
Title Race Condition in Guest Magic Link Authentication Allows Token Reuse
Weaknesses CWE-367
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}


Subscriptions

Mattermost Mattermost Mattermost Server
cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-04-15T14:00:27.030Z

Reserved: 2026-03-05T11:34:57.712Z

Link: CVE-2026-3590

cve-icon Vulnrichment

Updated: 2026-04-15T14:00:23.071Z

cve-icon NVD

Status : Analyzed

Published: 2026-04-15T12:16:40.023

Modified: 2026-04-22T19:41:52.700

Link: CVE-2026-3590

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T13:38:28Z

Weaknesses