{"id":"CVE-2026-16049","state":"PUBLISHED","title":"_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_","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","publishedAt":"2026-08-17T14:25:45.816Z","updatedAt":"2026-08-17T15:26:18.140Z","severity":{"score":3.9,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"10.20.11","versionType":"semver"},{"version":"0","status":"affected","lessThanOrEqual":"11.5.7","versionType":"semver"},{"version":"11.9.0","status":"unaffected"},{"version":"10.11.21","status":"unaffected"},{"version":"11.7.6","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-862"],"ingestedAt":"2026-10-29T20:11:00.674Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/16xxx/CVE-2026-16049.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-16049","state":"PUBLISHED","datePublished":"2026-08-17T14:25:45.816Z","dateUpdated":"2026-08-17T15:26:18.140Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-07-17T09:46:23.992Z"},"containers":{"cna":{"title":"_GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_","descriptions":[{"lang":"en","value":"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"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"10.20.11","versionType":"semver"},{"version":"0","status":"affected","lessThanOrEqual":"11.5.7","versionType":"semver"},{"version":"11.9.0","status":"unaffected"},{"version":"10.11.21","status":"unaffected"},{"version":"11.7.6","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00673","tags":["vendor-advisory"]}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"NONE","availabilityImpact":"NONE","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","baseSeverity":"LOW","baseScore":3.9},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-862","lang":"en","type":"CWE","description":"CWE-862: Missing Authorization"}]}],"providerMetadata":{"shortName":"Mattermost","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateUpdated":"2026-08-17T14:25:45.816Z"},"credits":[{"lang":"en","type":"finder","value":"MindFlare007"}],"solutions":[{"value":"Update Mattermost Plugins to versions 11.9.0, 10.11.21, 11.7.6 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00673","defect":["https://mattermost.atlassian.net/browse/MM-68836"],"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-17T14:51:08.354829Z","id":"CVE-2026-16049","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-17T15:26:18.140Z"}}]}}}