{"id":"CVE-2026-9708","state":"PUBLISHED","title":"Incoming webhook user attribution via unvalidated webhook owner","description":"Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683","publishedAt":"2026-07-13T08:00:10.707Z","updatedAt":"2026-07-13T14:45:16.207Z","severity":{"score":4.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.2","versionType":"semver"},{"version":"11.6.0","status":"affected","lessThanOrEqual":"11.6.4","versionType":"semver"},{"version":"10.11.0","status":"affected","lessThanOrEqual":"10.11.19","versionType":"semver"},{"version":"11.8.0","status":"unaffected"},{"version":"11.7.3","status":"unaffected"},{"version":"11.6.5","status":"unaffected"},{"version":"10.11.20","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-639"],"ingestedAt":"2026-10-29T20:13:52.441Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/9xxx/CVE-2026-9708.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-9708","state":"PUBLISHED","datePublished":"2026-07-13T08:00:10.707Z","dateUpdated":"2026-07-13T14:45:16.207Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-05-27T13:46:27.399Z"},"containers":{"cna":{"title":"Incoming webhook user attribution via unvalidated webhook owner","descriptions":[{"lang":"en","value":"Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.2","versionType":"semver"},{"version":"11.6.0","status":"affected","lessThanOrEqual":"11.6.4","versionType":"semver"},{"version":"10.11.0","status":"affected","lessThanOrEqual":"10.11.19","versionType":"semver"},{"version":"11.8.0","status":"unaffected"},{"version":"11.7.3","status":"unaffected"},{"version":"11.6.5","status":"unaffected"},{"version":"10.11.20","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00683","tags":["vendor-advisory"]}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"HIGH","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N","baseSeverity":"MEDIUM","baseScore":4.9},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-639","lang":"en","type":"CWE","description":"CWE-639: Authorization Bypass Through User-Controlled Key"}]}],"providerMetadata":{"shortName":"Mattermost","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateUpdated":"2026-07-13T08:00:10.707Z"},"credits":[{"lang":"en","type":"finder","value":"arang"}],"solutions":[{"value":"Update Mattermost to versions 11.8.0, 11.7.3, 11.6.5, 10.11.20 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00683","defect":["https://mattermost.atlassian.net/browse/MM-69009"],"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-13T14:44:57.510921Z","id":"CVE-2026-9708","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":"2026-07-13T14:45:16.207Z"}}]}}}