Description
Mattermost Plugins versions <=11.8 10.20.11 11.5.7.0 _The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied_ {{post_id}}_, and fails to validate the_ {{web_url}} _parameter against the configured GitLab instance, which allows an authenticated attacker to inject bot-authored messages containing arbitrary URLs into channels they do not have access to via the_ {{createIssue}} _and_ {{attachCommentToIssue}} _API endpoints._ Mattermost Advisory ID: MMSA-2026-00673
Published: 2026-08-17
Score: 3.9 Low
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

Update Mattermost Plugins to versions 11.9.0, 10.11.21, 11.7.6 or higher.

Tracking

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Advisories

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References
History

Mon, 17 Aug 2026 14:45:00 +0000

Type Values Removed Values Added
Description Mattermost Plugins versions <=11.8 10.20.11 11.5.7.0 _The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied_ {{post_id}}_, and fails to validate the_ {{web_url}} _parameter against the configured GitLab instance, which allows an authenticated attacker to inject bot-authored messages containing arbitrary URLs into channels they do not have access to via the_ {{createIssue}} _and_ {{attachCommentToIssue}} _API endpoints._ Mattermost Advisory ID: MMSA-2026-00673
Title _GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 3.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}


Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-08-17T14:25:45.816Z

Reserved: 2026-07-17T09:46:23.992Z

Link: CVE-2026-16049

cve-icon Vulnrichment

No data.

cve-icon NVD

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cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses