CVE-2026-16049
MEDIUM
NVD
CVSS Score
4.3
Severity
MEDIUM
Published
Aug 17, 2026
Vendor
unknown
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