{"id":"CVE-2026-5139","state":"PUBLISHED","title":"GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration","description":"Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler, which allows any authenticated user to overwrite the global default GitLab instance configuration via the {{/gitlab connect <instance-name>}} slash command.. Mattermost Advisory ID: MMSA-2026-00644","publishedAt":"2026-06-22T13:34:21.247Z","updatedAt":"2026-06-22T15:39:29.821Z","severity":{"score":5.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.0","versionType":"semver"},{"version":"11.6.0","status":"affected","lessThanOrEqual":"11.6.2","versionType":"semver"},{"version":"11.5.0","status":"affected","lessThanOrEqual":"11.5.5","versionType":"semver"},{"version":"10.11.0","status":"affected","lessThanOrEqual":"10.11.17","versionType":"semver"},{"version":"11.8.0","status":"unaffected"},{"version":"11.7.1","status":"unaffected"},{"version":"11.6.3","status":"unaffected"},{"version":"11.5.6","status":"unaffected"},{"version":"10.11.18","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-862"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/5xxx/CVE-2026-5139.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-5139","state":"PUBLISHED","datePublished":"2026-06-22T13:34:21.247Z","dateUpdated":"2026-06-22T15:39:29.821Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-03-30T11:29:16.698Z"},"containers":{"cna":{"title":"GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration","descriptions":[{"lang":"en","value":"Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler, which allows any authenticated user to overwrite the global default GitLab instance configuration via the {{/gitlab connect <instance-name>}} slash command.. Mattermost Advisory ID: MMSA-2026-00644"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.0","versionType":"semver"},{"version":"11.6.0","status":"affected","lessThanOrEqual":"11.6.2","versionType":"semver"},{"version":"11.5.0","status":"affected","lessThanOrEqual":"11.5.5","versionType":"semver"},{"version":"10.11.0","status":"affected","lessThanOrEqual":"10.11.17","versionType":"semver"},{"version":"11.8.0","status":"unaffected"},{"version":"11.7.1","status":"unaffected"},{"version":"11.6.3","status":"unaffected"},{"version":"11.5.6","status":"unaffected"},{"version":"10.11.18","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00644","tags":["vendor-advisory"]}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"LOW","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L","baseSeverity":"MEDIUM","baseScore":5.4},"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":"2026-06-22T13:34:21.247Z"},"credits":[{"lang":"en","type":"finder","value":"hunterxluxhug"}],"solutions":[{"value":"Update Mattermost to versions 11.8.0, 11.7.1, 11.6.3, 11.5.6, 10.11.18 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00644","defect":["https://mattermost.atlassian.net/browse/MM-68132"],"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-22T15:39:17.436366Z","id":"CVE-2026-5139","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":"2026-06-22T15:39:29.821Z"}}]}}}