---
title: "CVE-2026-108261: TinaCMS admin preview iframe loads an attacker-controlled origin from the URL fragment"
url: https://erroneo.us/security/cve/CVE-2026-108261/
description: "CVE-2026-108261 (tinacms (npm)): Tina is a headless content management system. Prior to tinacms 3.14.0 and @tinacms/app 2.5.14, the /~/ admin preview route…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-10-09
date_modified: 2026-10-13
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-108261"
kev: false
cvss: 9.3
epss: 0.0016
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-108261: TinaCMS admin preview iframe loads an attacker-controlled origin from the URL fragment

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.2% , percentile 5: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 5% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
- Only applies if your dependency tree includes tinacms (npm) <= 3.13.0, fixed in 3.14.0 ; @tinacms/app (npm) <= 2.5.13, fixed in 2.5.14 . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- npm `tinacms` <= 3.13.0 → fixed: 3.14.0
- npm `@tinacms/app` <= 2.5.13 → fixed: 2.5.14

## Affected products (CVE record)

- tinacms tinacms: < 3.14.0
- @tinacms app: < 2.5.14

## Severity

- GitHub_M CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.16% probability of exploitation activity in the next 30 days; percentile 5.

## Sources

- [GitHub Advisory GHSA-x34j-47hf-4xg7](https://github.com/advisories/GHSA-x34j-47hf-4xg7)
- [CVE.org record CVE-2026-108261](https://www.cve.org/CVERecord?id=CVE-2026-108261)
- [NVD entry CVE-2026-108261](https://nvd.nist.gov/vuln/detail/CVE-2026-108261)
- [github.com](https://github.com/tinacms/tinacms/security/advisories/GHSA-x34j-47hf-4xg7)
- [github.com](https://github.com/tinacms/tinacms/pull/7522)
- [github.com](https://github.com/tinacms/tinacms/commit/b57dbf4b56201aef15cd92caa49fd12ab96bbecf)
- [github.com](https://github.com/tinacms/tinacms/releases/tag/@tinacms/app@2.5.14)
- [github.com](https://github.com/tinacms/tinacms/releases/tag/tinacms@3.14.0)

---
Source page: https://erroneo.us/security/cve/CVE-2026-108261/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt