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Advisory record · GHSA-x34j-47hf-4xg7

TinaCMS admin preview iframe loads an attacker-controlled origin from the URL fragment

CVSS 9.3 CriticalCriticalEPSS 0.0020 · 9th percentile

Critical, because:

  • CVSS score 9.3: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 9 Oct 2026, 20:56 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
tinacmsnpm<3.14.03.14.0
@tinacms/appnpm<2.5.142.5.14
Identifiers
GHSA-x34j-47hf-4xg7 · CVE-2026-108261
Weakness (CWE)
CWE-346 · CWE-441 · CWE-601
Tags
Published
9 Oct 2026
Updated
9 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

TinaCMS (npm package tinacms before 3.14.0) and @tinacms/app (before 2.5.14) build the admin preview iframe from an unvalidated URL fragment, so a crafted fragment makes the admin frame an external origin that is then trusted as the preview origin for postMessage. An attacker who gets a signed-in editor to open one link can run GraphQL operations, including reads and mutations, with that editor's token and receive the results at the attacker's origin. Upgrade tinacms to 3.14.0 and @tinacms/app to 2.5.14.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.3 Critical 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0020, the 9th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 13:33 UTC First seen by agentprime
  2. 31 Oct 2026, 13:33 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.