{"id":"CVE-2026-16049","aliases":["EUVD-2026-60209","GHSA-vr3j-2q9w-h26r"],"status":"published","title":"_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_","description":"Mattermost Plugins versions \u003c=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","severity":{"version":"3.1","score":3.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00294,"percentile":0.22185,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-862"],"published":"2026-08-17T14:25:45Z","modified":"2026-08-18T15:04:46Z","products":[{"vendor":"mattermost","product":"mattermost"}],"references":[{"url":"https://mattermost.com/security-updates","tags":["vendor-advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-16049"},{"url":"https://github.com/advisories/GHSA-vr3j-2q9w-h26r"}],"sources":{"cve":[{"id":"CVE-2026-16049","title":"_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_","description":"Mattermost Plugins versions \u003c=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","status":"published","published":"2026-08-17T14:25:45.816Z","modified":"2026-08-17T15:26:18.14Z","cvss":[{"version":"3.1","score":3.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low","assessor":"cna"}],"cwes":["CWE-862"],"updated_at":"2026-11-02T14:20:10.870108Z"}],"euvd":[{"id":"EUVD-2026-60209","description":"Mattermost Plugins versions \u003c=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","status":"published","published":"2026-08-17T14:25:45Z","modified":"2026-08-17T15:26:18Z","cvss":[{"version":"3.1","score":3.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low"}],"updated_at":"2026-11-02T18:01:49.335011Z"}],"ghsa":[{"id":"GHSA-vr3j-2q9w-h26r","title":"Mattermost Plugins versions \u003c=11.8 10.20.11 11.5.7.0 _The Mattermost GitLab plugin fails to...","description":"Mattermost Plugins versions \u003c=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","status":"published","published":"2026-08-17T15:30:40Z","modified":"2026-08-17T15:30:49Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-862"],"updated_at":"2026-11-02T15:10:34.652326Z"}],"nvd":[{"id":"CVE-2026-16049","description":"Mattermost Plugins versions \u003c=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","status":"published","published":"2026-08-17T15:16:54.42Z","modified":"2026-08-18T15:04:46.61Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-862"],"updated_at":"2026-11-02T14:12:38.647684Z"}]}}