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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-63123: 0.26% estimated exploitation activity in the next 30 days; percentile 18.39 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A browser-based cross-origin request flaw in the Tina dev server allows an attacker-controlled website to cause arbitrary file creation inside the configured media upload directory on a developer machine running tinacms dev. No manual file upload is required. The attacker page builds the multipart request in JavaScript and sends it directly to the local Tina server. The browser blocks access to the response because of CORS, but the server still processes the request and writes the file. Details The issue is in the dev server path of @tinacms/cli. The Vite dev server installs CORS middleware: For disallowed origins, the origin callback only returns false to the CORS library: That does not reject the request server-side. The same request is still routed into the upload handler: The upload handler then accepts attacker-controlled path and body data and writes the file: This is exploitable because multipart/form-data is a simple browser request and does not require a preflight.…

Published by the source

19 Aug 2026, 21:56 UTC

Last modified by the source

21 Aug 2026, 18:31 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rgr9-r7mj-mf6x

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# Patch Next advisory brief: CVE-2026-63123

Advisory: Tina: Cross-origin `POST /media/upload/*` requests can write arbitrary files into the Tina dev server media root
IDs: CVE-2026-63123, GHSA-rgr9-r7mj-mf6x
Record: https://patchnext.com/advisories/cve-2026-63123 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @tinacms/cli 2.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @tinacms/cli: affected < 2.5.2; fixed in 2.5.2

## Suggested inspection (read-only)
- `npm ls @tinacms/cli --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @tinacms/cli.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rgr9-r7mj-mf6x (GitHub-reviewed advisory GHSA-rgr9-r7mj-mf6x lists affected ranges: npm @tinacms/cli >=0 <2.5.2)

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