Description
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649
Published: 2026-06-12
Score: 5.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

Vendor Solution

Update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.

Tracking

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Advisories

No advisories yet.

References
Link Providers
https://mattermost.com/security-updates cve-icon cve-icon
History

Fri, 12 Jun 2026 18:45:00 +0000

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

Fri, 12 Jun 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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

Fri, 12 Jun 2026 17:15:00 +0000

Type Values Removed Values Added
Description Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649
Title Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server
Weaknesses CWE-200
References
Metrics cvssV3_1

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

Subscriptions

Mattermost Mattermost
cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-06-12T17:18:30.553Z

Reserved: 2026-04-09T19:20:26.868Z

Link: CVE-2026-6046

cve-icon Vulnrichment

Updated: 2026-06-12T17:18:27.704Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-06-12T17:16:26.957

Modified: 2026-06-15T20:56:44.703

Link: CVE-2026-6046

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-12T19:00:21Z

Weaknesses