{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-28736","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","state":"PUBLISHED","assignerShortName":"Mattermost","dateReserved":"2026-04-03T13:10:59.177Z","datePublished":"2026-04-03T13:25:53.399Z","dateUpdated":"2026-04-03T14:54:37.869Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Focalboard","vendor":"Mattermost","versions":[{"lessThanOrEqual":"8.0","status":"affected","version":"0","versionType":"semver"}]}],"credits":[{"lang":"en","type":"finder","value":"Siam Thanat Hack Company Limited"}],"descriptions":[{"lang":"en","value":"** UNSUPPORTED WHEN ASSIGNED ** Focalboard version 8.0 fails to validate file ownership when serving uploaded files. This allows an authenticated attacker who knows a victim's fileID to read the content of the file. NOTE: Focalboard as a standalone product is not maintained and no fix will be issued."}],"tags":["unsupported-when-assigned"],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"NONE","availabilityImpact":"NONE","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","baseSeverity":"MEDIUM","baseScore":4.3},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"lang":"en","type":"CWE","description":"CWE-639: Authorization Bypass Through User-Controlled Key","cweId":"CWE-639"}]}],"references":[{"url":"https://github.com/mattermost-community/focalboard","name":"Focalboard Repository (Unmaintained)","tags":["product"]}],"source":{"discovery":"EXTERNAL"},"title":"Focalboard IDOR in file content endpoint allows cross-user file access (unsupported product, no fix)","providerMetadata":{"orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","shortName":"Mattermost","dateUpdated":"2026-04-03T13:25:53.399Z"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-03T14:53:54.422014Z","id":"CVE-2026-28736","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-04-03T14:54:37.869Z"}}]}}