CVE-2026-16049
_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_
CVSS Score
3.9
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-862 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Aug 17, 2026 |
| Last Updated | Aug 17, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
Affected Versions
Mattermost / Mattermost
0 ≤ 10.20.11 0 ≤ 11.5.7
Credits
MindFlare007