{"api_version":"1","generated_at":"2026-09-26T14:35:56+00:00","cve":"CVE-2026-75588","urls":{"html":"https://cve.report/CVE-2026-75588","api":"https://cve.report/api/cve/CVE-2026-75588.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-75588","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-75588"},"summary":{"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","state":"PUBLISHED","assigner":"Mattermost","published_at":"2026-09-17 16:17:41","updated_at":"2026-09-18 13:46:33"},"problem_types":["CWE-1287","CWE-1287 CWE-1287: Improper Validation of Specified Type of Input"],"metrics":[{"version":"3.1","source":"responsibledisclosure@mattermost.com","type":"Secondary","score":"2.6","severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","baseScore":2.6,"baseSeverity":"LOW","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"2.6","severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","data":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":2.6,"baseSeverity":"LOW","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","version":"3.1"}}],"references":[{"url":"https://mattermost.com/security-updates","name":"https://mattermost.com/security-updates","refsource":"responsibledisclosure@mattermost.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-75588","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-75588","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"affected 6.2.2 semver","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 6.3.0","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 6.2.3.0","platforms":[]}],"timeline":[],"solutions":[{"source":"CNA","title":"","value":"Update Mattermost Desktop App to versions 6.3.0, 6.2.3.0 or higher.","time":"","lang":"en"}],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"Juho Forsén","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"75588","cve":"CVE-2026-75588","epss":"0.001670000","percentile":"0.063580000","score_date":"2026-09-20","updated_at":"2026-09-21 00:10:10"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-75588","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-09-17T19:21:58.878556Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-09-17T19:22:50.101Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Mattermost","vendor":"Mattermost","versions":[{"lessThanOrEqual":"6.2.2","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"6.3.0"},{"status":"unaffected","version":"6.2.3.0"}]}],"credits":[{"lang":"en","type":"finder","value":"Juho Forsén"}],"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"}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":2.6,"baseSeverity":"LOW","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1287","description":"CWE-1287: Improper Validation of Specified Type of Input","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-17T15:09:40.829Z","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","shortName":"Mattermost"},"references":[{"name":"MMSA-2026-00717","tags":["vendor-advisory"],"url":"https://mattermost.com/security-updates"}],"solutions":[{"lang":"en","value":"Update Mattermost Desktop App to versions 6.3.0, 6.2.3.0 or higher."}],"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\"}"},"title":"Mattermost Desktop App plugin popout scheme validation bypass","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","assignerShortName":"Mattermost","cveId":"CVE-2026-75588","datePublished":"2026-09-17T15:09:40.829Z","dateReserved":"2026-08-17T22:19:32.227Z","dateUpdated":"2026-09-17T19:22:50.101Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 16:17:41","lastModifiedDate":"2026-09-18 13:46:33","problem_types":["CWE-1287","CWE-1287 CWE-1287: Improper Validation of Specified Type of Input"],"metrics":{"cvssMetricV31":[{"source":"responsibledisclosure@mattermost.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N","baseScore":2.6,"baseSeverity":"LOW","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE"},"exploitabilityScore":1.2,"impactScore":1.4}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-17T19:21:58.878556Z","id":"CVE-2026-75588","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"75588","Ordinal":"1","Title":"Mattermost Desktop App plugin popout scheme validation bypass","CVE":"CVE-2026-75588","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"75588","Ordinal":"1","NoteData":"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","Type":"Description","Title":"Mattermost Desktop App plugin popout scheme validation bypass"}]}}}