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

> An attacker can trick an editor into loading a malicious iframe, allowing unauthorized GraphQL reads and mutations with editor credentials.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 9 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-x34j-47hf-4xg7

## What is CVE-2026-108261?

CVE-2026-108261 is a critical vulnerability in @tinacms app, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-601 (URL Redirection to Untrusted Site), CWE-441 (Unintended Proxy or Intermediary), CWE-346 (Origin Validation Error)

## Which versions are affected by CVE-2026-108261?

4 open source packages ship an affected version, including @tinacms/app and tinacms.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@tinacms/app` | npm | All versions | 2.5.14 |
| `@tinacms/app` | npm | All versions | 2.5.14 |
| `tinacms` | npm | All versions | 3.14.0 |
| `tinacms` | npm | All versions | 3.14.0 |

## How do I fix CVE-2026-108261?

Upgrade @tinacms/app to 2.5.14 or later.

## Is CVE-2026-108261 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-108261 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-108261 and fix it if it is affected.

What it is: CVE-2026-108261 is a critical vulnerability in @tinacms app, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-108261 exists.

Affected packages and fixed versions:
- @tinacms/app (npm): affected all versions; fixed in 2.5.14
- @tinacms/app (npm): affected all versions; fixed in 2.5.14
- tinacms (npm): affected all versions; fixed in 3.14.0
- tinacms (npm): affected all versions; fixed in 3.14.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-108261/ (Markdown: https://insights.sbomify.com/CVE-2026-108261/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-108261
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-108261
- OSV: https://osv.dev/vulnerability/CVE-2026-108261

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-108261/
Summaries are generated and may contain mistakes; the official description above is the record.