{"id":"CVE-2026-55660","state":"PUBLISHED","title":"TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover","description":"Tina is a headless content management system. In versions prior to @tinacms/app 2.5.6 and tinacms 3.9.3, cross-origin postMessage handlers and a rich-text URL-sanitization bypass enable stored XSS and session takeover. The library registers window message listeners — the useTina overlay handler, the OAuth authentication popup handler, and the admin↔preview iframe GraphQL reducer — that act on event.data without verifying event.origin or event.source and post messages using non-specific target origins, while insufficient URL sanitization in rich-text content allows malicious URLs to persist and execute. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session. This issue has been fixed in versions @tinacms/app 2.5.6 and tinacms 3.9.3.","publishedAt":"2026-07-01T21:00:27.321Z","updatedAt":"2026-07-02T12:43:47.881Z","severity":{"score":7.6,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["tinacms tinacms","tinacms @tinacms/app"],"affected":[{"vendor":"tinacms","product":"tinacms","versions":[{"version":"< 3.9.3","status":"affected"}]},{"vendor":"tinacms","product":"@tinacms/app","versions":[{"version":"< 2.5.6","status":"affected"}]}],"references":["https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f","https://github.com/tinacms/tinacms/pull/7056"],"weaknesses":["CWE-79","CWE-346","CWE-601","CWE-940"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55660.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55660","state":"PUBLISHED","datePublished":"2026-07-01T21:00:27.321Z","dateUpdated":"2026-07-02T12:43:47.881Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-17T00:05:03.777Z"},"containers":{"cna":{"title":"TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover","descriptions":[{"lang":"en","value":"Tina is a headless content management system. In versions prior to @tinacms/app 2.5.6 and tinacms 3.9.3, cross-origin postMessage handlers and a rich-text URL-sanitization bypass enable stored XSS and session takeover. The library registers window message listeners — the useTina overlay handler, the OAuth authentication popup handler, and the admin↔preview iframe GraphQL reducer — that act on event.data without verifying event.origin or event.source and post messages using non-specific target origins, while insufficient URL sanitization in rich-text content allows malicious URLs to persist and execute. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session. This issue has been fixed in versions @tinacms/app 2.5.6 and tinacms 3.9.3."}],"affected":[{"vendor":"tinacms","product":"tinacms","versions":[{"version":"< 3.9.3","status":"affected"}]},{"vendor":"tinacms","product":"@tinacms/app","versions":[{"version":"< 2.5.6","status":"affected"}]}],"references":[{"url":"https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f","name":"https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/tinacms/tinacms/pull/7056","name":"https://github.com/tinacms/tinacms/pull/7056","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":7.6,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-346","lang":"en","description":"CWE-346: Origin Validation Error","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-601","lang":"en","description":"CWE-601: URL Redirection to Untrusted Site ('Open Redirect')","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-940","lang":"en","description":"CWE-940: Improper Verification of Source of a Communication Channel","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-01T21:00:27.321Z"},"source":{"advisory":"GHSA-g5qx-h5f3-mp2f","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-02T12:43:41.136950Z","id":"CVE-2026-55660","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-02T12:43:47.881Z"}}]}}}