CVE-2026-55660

HIGHPre-NVD 7.67.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 90% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
7.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.6Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.6
EG Score
7.6(medium)
EPSS
9.5%
KEV
Not listed

Published

June 19, 2026

Last Modified

July 2, 2026

Advisory Details (2)

Auto-updated Jul 1, 2026
Patch available. Sources: github, github_pr.
github Patch Available

TinaCMS cross-window postMessage handlers do not validate message origin or source, enabling message forgery and OAuth session takeover · Advisory · tinacms/tinacms · GitHub

https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f
github_pr Patch Available

Harden message origin checks and rich-text URL sanitization

Patch available: tinacms/tinacms [email protected] (PR #7056 merged 2026-06-15)

https://github.com/tinacms/tinacms/pull/7056

Vendor Advisories for CVE-2026-55660(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 1 ecosystem)
npm(2)
PackageVulnerable rangeFixed inDependents
tinacms—3.9.3—
@tinacms/app—2.5.6—

Weakness Classification(4)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 20× in last 7d / 21× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-07 02:33 UTCEG score recompute
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 14:20 UTCEG score recompute
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-06 02:06 UTCEG score recompute
  8. 2026-07-05 13:52 UTCEG score recompute
  9. 2026-07-05 02:31 UTCEPSS rescore
  10. 2026-07-05 02:30 UTCEPSS rescore
  11. 2026-07-05 01:40 UTCEG score recompute
  12. 2026-07-04 13:25 UTCEG score recompute
  13. 2026-07-04 06:31 UTCEPSS rescore
  14. 2026-07-04 06:31 UTCEPSS rescore
  15. 2026-07-04 01:12 UTCEG score recompute
  16. 2026-07-03 12:58 UTCEG score recompute
  17. 2026-07-02 23:36 UTCEG score recompute
  18. 2026-07-02 11:24 UTCEG score recompute
  19. 2026-07-01 23:10 UTCEG score recompute▲ 7.60
  20. 2026-07-01 23:08 UTCNVD updateCVSS v3 → 7.6 · CVSS v4 → 7.6
  21. 2026-06-19 21:23 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55660?
CVE-2026-55660 is a high vulnerability published on June 19, 2026. 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,…
When was CVE-2026-55660 disclosed?
CVE-2026-55660 was first published in the National Vulnerability Database on June 19, 2026, with the most recent update on July 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55660 actively exploited?
CVE-2026-55660 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 9.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55660?
CVE-2026-55660 has a CVSS v3 base score of 7.6 (NVD).
How do I remediate CVE-2026-55660?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55660, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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