GHSA-p6c5-mjgj-m4rm

Duplicate Advisory: Parse Server vulnerable to stored XSS via malformed Content-Type bypassing file upload extension blocklist

Published

2026-07-11

Modified

2026-10-29

Sources

github-advisory

Summary

### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-r899-h629-j84r. This link is maintained to preserve external references. ### Original Description Parse Server is affected by a stored cross-site scripting (XSS) vulnerability in versions >= 9.0.0, < 9.10.0-alpha.2 and <= 8.6.83. When an uploaded file's extension is not recognized by the mime package, Parse Server preserves the client-supplied Content-Type. A malformed Content-Type that is not a valid type/subtype media type (e.g., 'image', 'image/', or 'image//svg+xml') bypasses the fileUpload.fileExtensions blocklist and is stored unchanged. On storage adapters that persist and serve the uploaded Content-Type (such as Amazon S3, Google Cloud Storage, or Azure Blob Storage), a browser cannot parse the malformed value and falls back to MIME-sniffing; a file whose body begins with HTML is rendered as HTML, executing embedded script in the application's origin against other users who open the file URL. The default GridFS storage adapter is not affected. Fixed in 9.10.0-alpha.2 and 8.6.84.

Affected packages

Remediation: No patched version is listed by GitHub.

References

• https://github.com/advisories/GHSA-p6c5-mjgj-m4rm