{"id":"CVE-2026-55660","aliases":["EUVD-2026-41143","GHSA-g5qx-h5f3-mp2f"],"status":"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.","severity":{"version":"4.0","score":7.6,"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00279,"percentile":0.20563,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-346","CWE-601","CWE-79","CWE-940"],"published":"2026-06-19T21:15:29Z","modified":"2026-10-28T02:30:41Z","fixes":[{"ecosystem":"npm","package":"tinacms","fixed_in":["3.9.3"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@tinacms/app","fixed_in":["2.5.6"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"tinacms","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.9.3"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@tinacms/app","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.5.6"}]}]},{"source":"osv","ecosystem":"npm","package":"tinacms","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.9.3"}]}]},{"source":"osv","ecosystem":"npm","package":"@tinacms/app","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.5.6"}]}]}],"products":[{"vendor":"tinacms","product":"@tinacms/app"},{"vendor":"tinacms","product":"tinacms"}],"references":[{"url":"https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/tinacms/tinacms/pull/7056","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/advisories/GHSA-g5qx-h5f3-mp2f"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55660.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55660","tags":["advisory"]},{"url":"https://github.com/tinacms/tinacms","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-55660","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.","status":"published","published":"2026-07-01T21:00:27.321Z","modified":"2026-07-02T12:43:47.881Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high","assessor":"cna"}],"cwes":["CWE-79","CWE-346","CWE-601","CWE-940"],"updated_at":"2026-11-02T14:20:12.260247Z"}],"euvd":[{"id":"EUVD-2026-41143","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.","status":"published","published":"2026-07-01T21:00:27Z","modified":"2026-07-02T12:43:47Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"}],"updated_at":"2026-11-02T18:20:17.786883Z"}],"ghsa":[{"id":"GHSA-g5qx-h5f3-mp2f","title":"TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover","description":"TinaCMS 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. 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.\n\nFixed in [#7056](https://github.com/tinacms/tinacms/pull/7056) by allow-listing trusted origins and verifying event.source (isFromAdmin, isFromTrustedPreviewOrigin), and by posting only to explicit target origins (never \"*\").\n\nNote: the rich-text URL-sanitization issue previously bundled here has been split into its own advisory (GHSA-2vcc-5v34-9jc8) so each vulnerability can receive a distinct CVE.","status":"published","published":"2026-06-19T21:15:29Z","modified":"2026-06-19T21:15:29Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-79","CWE-346","CWE-601","CWE-940"],"updated_at":"2026-11-02T14:40:31.656952Z"}],"nvd":[{"id":"CVE-2026-55660","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.","status":"published","published":"2026-07-01T21:17:03.96Z","modified":"2026-07-02T17:45:00.78Z","cvss":[{"version":"4.0","score":7.6,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-79","CWE-346","CWE-601","CWE-940"],"updated_at":"2026-11-02T14:12:27.199837Z"}],"osv":[{"id":"CVE-2026-55660","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.","status":"published","published":"2026-07-01T21:00:27.321Z","modified":"2026-10-28T02:30:41.933929315Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"}],"cwes":["CWE-346","CWE-601","CWE-79","CWE-940"],"updated_at":"2026-11-02T15:45:11.22012Z"},{"id":"GHSA-g5qx-h5f3-mp2f","title":"TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover","description":"TinaCMS 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. 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.\n\nFixed in [#7056](https://github.com/tinacms/tinacms/pull/7056) by allow-listing trusted origins and verifying event.source (isFromAdmin, isFromTrustedPreviewOrigin), and by posting only to explicit target origins (never \"*\").\n\nNote: the rich-text URL-sanitization issue previously bundled here has been split into its own advisory (GHSA-2vcc-5v34-9jc8) so each vulnerability can receive a distinct CVE.","status":"published","published":"2026-06-19T21:15:29Z","modified":"2026-09-10T03:50:49.428018311Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-346","CWE-601","CWE-79","CWE-940"],"updated_at":"2026-11-02T15:46:47.472172Z"}]}}