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Fencer Vulns
critical 9.3

CVE-2026-108261 json

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

published 2026-10-09 30 d ago modified 2026-10-16 23 d ago also GHSA-x34j-47hf-4xg7 , EUVD-2026-95990

cvss
9.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

Tina is a headless content management system. Prior to tinacms 3.14.0 and @tinacms/app 2.5.14, the /~/* admin preview route in packages/tinacms/src/admin/index.tsx can turn an attacker-controlled hash-router splat into an off-origin iframe URL through packages/@tinacms/app/src/preview.tsx, while packages/@tinacms/app/src/lib/preview-origin.ts derives expectedOrigin from that same URL for the GraphQL message channel in packages/@tinacms/app/src/lib/graphql-reducer.ts. An unauthenticated attacker can send a crafted link to a signed-in editor, cause the admin to frame an attacker origin, and have that frame treated as the trusted preview. The attacker-controlled frame can submit GraphQL reads or mutations that the admin executes with the editor credentials, exposing or modifying protected content. This issue is fixed in tinacms 3.14.0 and @tinacms/app 2.5.14.

Patch / fix

  • npm tinacms 3.14.0
  • npm @tinacms/app 2.5.14

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
26 d ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/tinacms/tinacms/security/advisories/GHSA-x34j-47hf-4xg7 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
GitHub 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm tinacms
<3.14.0
3.14.0
npm @tinacms/app
<2.5.14
2.5.14

Affected products

  • tinacms tinacms
  • @tinacms app

Classification

Weakness
  • CWE-346 Origin Validation Error
  • CWE-441 Unintended Proxy or Intermediary
  • CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.