{"cve":"CVE-2026-55660","nvd":{"published":"2026-07-01T21:17:03.960","modified":"2026-07-02T17:45:00.780","status":"Deferred","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.","cvss_v4":{"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","score":7.6},"cvss_v3":null,"cwes":["CWE-79","CWE-346","CWE-601","CWE-940"],"references":["https://github.com/tinacms/tinacms/pull/7056","https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:42:16.820116992+00:00"},"epss":{"cve":"CVE-2026-55660","score":0.00279,"percentile":0.2037,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-g5qx-h5f3-mp2f","url":"https://osv.dev/vulnerability/GHSA-g5qx-h5f3-mp2f","summary":"TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover","modified":"2026-09-10T03:50:49.428018311Z","packages":[{"ecosystem":"npm","name":"tinacms","purl":"pkg:npm/tinacms","ranges":["<3.9.3"],"fixed":["3.9.3"]},{"ecosystem":"npm","name":"@tinacms/app","purl":"pkg:npm/%40tinacms/app","ranges":["<2.5.6"],"fixed":["2.5.6"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}