# CVE-2026-63123: Tina: Cross-origin `POST /media/upload/*` requests can write arbitrary files into the Tina dev server media root

> A remote attacker can force a developer's browser to upload arbitrary files to the TinaCMS dev server media root via cross-origin requests.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/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:** 19 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** GHSA-rgr9-r7mj-mf6x

## What is CVE-2026-63123?

CVE-2026-63123 is a medium-severity vulnerability in tinacms, published on 19 Aug 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 2.5.2, the TinaCMS CLI package's Vite dev server packages/@tinacms/cli/src/next/vite/cors.ts origin callback returns false for a disallowed origin but does not reject the request, and packages/@tinacms/cli/src/next/vite/plugins.ts still routes POST /media/upload/* to mediaRouter.handlePost. The upload code in packages/@tinacms/cli/src/next/commands/dev-command/server/media.ts writes attacker-controlled multipart contents inside the configured media root. A remote attacker can cause a developer's browser to submit this state-changing request by inducing the developer to visit an attacker-controlled page while tinacms dev is running. This issue is fixed in version 2.5.2.

Weakness: CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2026-63123?

2 open source packages ship an affected version, including @tinacms/cli.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@tinacms/cli` | npm | All versions | 2.5.2 |
| `@tinacms/cli` | npm | All versions | 2.5.2 |

## How do I fix CVE-2026-63123?

Upgrade @tinacms/cli to 2.5.2 or later.

## Is CVE-2026-63123 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63123 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63123 and fix it if it is affected.

What it is: CVE-2026-63123 is a medium-severity vulnerability in tinacms, published on 19 Aug 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-2026-63123 exists.

Affected packages and fixed versions:
- @tinacms/cli (npm): affected all versions; fixed in 2.5.2
- @tinacms/cli (npm): affected all versions; fixed in 2.5.2

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-2026-63123/ (Markdown: https://insights.sbomify.com/CVE-2026-63123/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63123
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63123
- OSV: https://osv.dev/vulnerability/CVE-2026-63123

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63123/
Summaries are generated and may contain mistakes; the official description above is the record.