CVE-2026-16049

_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_

State: Published
Severity: 3.9 Low
Published: Aug 17, 2026
Updated: Aug 17, 2026
Reserved: Jul 17, 2026

Read the record on cve.org

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

Scores

CVSS	Score	Vector	Source
3.1	3.9 Low	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N	Mattermost

Weaknesses

CWE-862 Missing Authorization

Affected Products

Product	Versions
MattermostMattermost	10.20.11 and earlierAffected 11.5.7 and earlierAffected 11.9.0Not affected 10.11.21Not affected 11.7.6Not affected

References

MMSA-2026-00673vendor-advisory

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.