{"id":"CVE-2026-75588","state":"PUBLISHED","title":"Mattermost Desktop App plugin popout scheme validation bypass","description":"Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717","publishedAt":"2026-09-17T15:09:40.829Z","updatedAt":"2026-09-17T19:22:50.101Z","severity":{"score":2.6,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"6.2.2","versionType":"semver"},{"version":"6.3.0","status":"unaffected"},{"version":"6.2.3.0","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-1287"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/75xxx/CVE-2026-75588.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-75588","state":"PUBLISHED","datePublished":"2026-09-17T15:09:40.829Z","dateUpdated":"2026-09-17T19:22:50.101Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-08-17T22:19:32.227Z"},"containers":{"cna":{"title":"Mattermost Desktop App plugin popout scheme validation bypass","descriptions":[{"lang":"en","value":"Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"6.2.2","versionType":"semver"},{"version":"6.3.0","status":"unaffected"},{"version":"6.2.3.0","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00717","tags":["vendor-advisory"]}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","baseSeverity":"LOW","baseScore":2.6},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1287","lang":"en","type":"CWE","description":"CWE-1287: Improper Validation of Specified Type of Input"}]}],"providerMetadata":{"shortName":"Mattermost","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateUpdated":"2026-09-17T15:09:40.829Z"},"credits":[{"lang":"en","type":"finder","value":"Juho Forsén"}],"solutions":[{"value":"Update Mattermost Desktop App to versions 6.3.0, 6.2.3.0 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00717","defect":["https://mattermost.atlassian.net/browse/MM-69786"],"discovery":"{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-17T19:21:58.878556Z","id":"CVE-2026-75588","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":"2026-09-17T19:22:50.101Z"}}]}}}