---
cve: "CVE-2026-55660"
severity: "HIGH"
cvss: 7.6
epss: "0.3%"
vendor: "tinacms"
kev: false
exploited: false
published: "2026-07-01 21:17:03"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T21:46:56+02:00"
---

# CVE-2026-55660

> 7.6 HIGH · 🧪 PoC

## Beschreibung

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-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |

## Patch verfügbar (OSV)

- b6f613b1e3e093b47b8d5ebb732d4bb8dcdcccfd (Commit)
- b636a220d8f88ef50dcd364ae1109e5bbbfb8ddc (Commit)

## Referenzen

- <https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f>
- <https://github.com/tinacms/tinacms/pull/7056>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-55660) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_