{"id":"CVE-2026-18795","state":"PUBLISHED","title":"Missing server side validation allowed user to quarantine a DM and GM post","description":"Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756","publishedAt":"2026-10-16T07:01:22.549Z","updatedAt":"2026-10-16T11:59:42.771Z","severity":{"score":6.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.10.0","status":"affected","lessThanOrEqual":"11.10.0","versionType":"semver"},{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.9","versionType":"semver"},{"version":"11.9.0","status":"affected","lessThanOrEqual":"11.9.1","versionType":"semver"},{"version":"11.8.0","status":"affected","lessThanOrEqual":"11.8.5","versionType":"semver"},{"version":"11.11.0","status":"unaffected"},{"version":"11.10.1","status":"unaffected"},{"version":"11.7.10","status":"unaffected"},{"version":"11.9.2","status":"unaffected"},{"version":"11.8.6","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-862"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/18xxx/CVE-2026-18795.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-18795","state":"PUBLISHED","datePublished":"2026-10-16T07:01:22.549Z","dateUpdated":"2026-10-16T11:59:42.771Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-08-04T09:13:11.334Z"},"containers":{"cna":{"title":"Missing server side validation allowed user to quarantine a DM and GM post","descriptions":[{"lang":"en","value":"Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.10.0","status":"affected","lessThanOrEqual":"11.10.0","versionType":"semver"},{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.9","versionType":"semver"},{"version":"11.9.0","status":"affected","lessThanOrEqual":"11.9.1","versionType":"semver"},{"version":"11.8.0","status":"affected","lessThanOrEqual":"11.8.5","versionType":"semver"},{"version":"11.11.0","status":"unaffected"},{"version":"11.10.1","status":"unaffected"},{"version":"11.7.10","status":"unaffected"},{"version":"11.9.2","status":"unaffected"},{"version":"11.8.6","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00756","tags":["vendor-advisory"]}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"LOW","availabilityImpact":"LOW","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L","baseSeverity":"MEDIUM","baseScore":6.4},"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":"2026-10-16T07:01:22.549Z"},"credits":[{"lang":"en","type":"finder","value":"Harshil Sharma"}],"solutions":[{"value":"Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00756","defect":["https://mattermost.atlassian.net/browse/MM-70098"],"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-16T11:59:31.276508Z","id":"CVE-2026-18795","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":"2026-10-16T11:59:42.771Z"}}]}}}