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GHSA-g5qx-h5f3-mp2f — tinacms

Fix: tinacms/tinacms#7056

GHSA-g5qx-h5f3-mp2f is a Cross-site Scripting (XSS) vulnerability in tinacms. A fix is available for tinacms — see the affected versions and patch details below.

TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover

Also known asCVE-2026-55660
Published
Jun 19, 2026
Updated
Sep 10, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Sep 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-g5qx-h5f3-mp2f.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs21th percentile — riskier than 21% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

32other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
tinacmsnpm
44Kdownloads / week
@tinacms/appnpm
36Kdownloads / week

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.

Fixed in #7056 by allow-listing trusted origins and verifying event.source (isFromAdmin, isFromTrustedPreviewOrigin), and by posting only to explicit target origins (never "*").

Note: 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.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmtinacmsall versions3.9.3npm install tinacms@3.9.3
📦npm@tinacms/appall versions2.5.6npm install @tinacms/app@2.5.6

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tinacms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update tinacms to 3.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g5qx-h5f3-mp2f is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-g5qx-h5f3-mp2f can be triaged on real exposure rather than presence alone.

Tailored to GHSA-g5qx-h5f3-mp2f. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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. Fixed in [#7056](https://github.com/tinacms/tinacms/pull/7056) by allow-
O3 Security · Impact-Aware SCA

Is GHSA-g5qx-h5f3-mp2f in your dependencies?

O3 Security finds GHSA-g5qx-h5f3-mp2f across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-g5qx-h5f3-mp2f: tinacms | O3 Security