{"id":"CVE-2026-67204","state":"PUBLISHED","title":"BookStack < 26.05.4 Broken Access Control via Image Gallery API","description":"BookStack before 26.05.4 contains a broken access control vulnerability that allows authenticated API users with image-update or image-delete permissions to manipulate other users' avatars by exploiting missing content-type restrictions in the Image Gallery API endpoints. Attackers can supply a user avatar's ID to the API controller, which loads any image type without the web controller's gallery and drawio restrictions, and when the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check passes allowing the attacker to rename, replace, or delete the target user's avatar without requiring user-management permission.","publishedAt":"2026-08-24T15:33:13.649Z","updatedAt":"2026-10-01T15:20:17.762Z","severity":{"score":5.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","source":"VulnCheck"},"assigner":"VulnCheck","products":["BookStackApp BookStack"],"affected":[{"vendor":"BookStackApp","product":"BookStack","packageURL":"pkg:github/BookStackApp/BookStack","defaultStatus":"affected","versions":[{"version":"0","status":"affected","lessThan":"26.05.4","versionType":"custom"}],"repo":"https://github.com/BookStackApp/BookStack"}],"references":["https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/","https://codeberg.org/bookstack/bookstack/releases/tag/v26.05.4","https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4","https://www.vulncheck.com/advisories/bookstack-broken-access-control-via-image-gallery-api"],"weaknesses":["CWE-863"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/67xxx/CVE-2026-67204.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-67204","state":"PUBLISHED","datePublished":"2026-08-24T15:33:13.649Z","dateUpdated":"2026-10-01T15:20:17.762Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-07-28T16:06:49.775Z"},"containers":{"cna":{"title":"BookStack < 26.05.4 Broken Access Control via Image Gallery API","descriptions":[{"lang":"en","value":"BookStack before 26.05.4 contains a broken access control vulnerability that allows authenticated API users with image-update or image-delete permissions to manipulate other users' avatars by exploiting missing content-type restrictions in the Image Gallery API endpoints. Attackers can supply a user avatar's ID to the API controller, which loads any image type without the web controller's gallery and drawio restrictions, and when the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check passes allowing the attacker to rename, replace, or delete the target user's avatar without requiring user-management permission."}],"affected":[{"vendor":"BookStackApp","product":"BookStack","packageURL":"pkg:github/BookStackApp/BookStack","defaultStatus":"affected","versions":[{"version":"0","status":"affected","lessThan":"26.05.4","versionType":"custom"}],"repo":"https://github.com/BookStackApp/BookStack"}],"references":[{"url":"https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/","name":"Maintainer Blog","tags":["vendor-advisory"]},{"url":"https://codeberg.org/bookstack/bookstack/releases/tag/v26.05.4","name":"Codeberg Release Notes","tags":["release-notes"]},{"url":"https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4","name":"BookStack v26.05.4 Release Notes","tags":["release-notes"]},{"url":"https://www.vulncheck.com/advisories/bookstack-broken-access-control-via-image-gallery-api","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"LOW","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"MEDIUM","baseScore":5.3,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"LOW","version":"3.1","baseSeverity":"MEDIUM","baseScore":5.4,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-863","lang":"en","description":"Incorrect Authorization","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-10-01T15:20:17.762Z"},"tags":["x_open-source"],"datePublic":"2026-08-24T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*","versionEndExcluding":"26.05.4"}]}]}],"credits":[{"lang":"en","value":"ByteMe.Red","type":"finder"},{"lang":"en","value":"VulnCheck","type":"coordinator"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"vulncheck"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-24T17:20:05.562340Z","id":"CVE-2026-67204","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":"2026-08-24T17:20:18.693Z"}}]}}}