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

Source: https://junglewise.ai/threats/duplicate-advisory-parse-server-vulnerable-to-stored-xss-via-malformed-00d8867c  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-11  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 4 · Published 2026-07-11

### 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This advisory has been withdrawn because it is a duplicate of GHSA-r899-h629-j84r.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.

Technologies: [parse-server (npm)](https://junglewise.ai/threats/technologies/parse-server). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 4, published 11 July 2026.

**Which products and versions are affected?** parse-server (npm) >= 9.0.0, < 9.10.0-alpha.2, SEMVER:introduced=9.0.0.

**Is there a fix for This vulnerability?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected?** Check whether you run parse-server (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- parse-server (npm) >= 9.0.0, < 9.10.0-alpha.2, SEMVER:introduced=9.0.0

## Related threats

- [Parse Server stored XSS via malformed Content-Type bypass](https://junglewise.ai/threats/cve-2026-61448-parse-server-stored-xss-via-malformed-content-type-bypass)
- [Parse Server information disclosure in LiveQuery ACL transitions](https://junglewise.ai/threats/cve-2026-57481-parse-server-information-disclosure-in-livequery-acl-transitions)
- [Parse Community Parse Server denial of service via nested query operators](https://junglewise.ai/threats/cve-2026-57480-parse-community-parse-server-denial-of-service-via-nested-query)
- [Parse Server stored XSS via file upload extension bypass](https://junglewise.ai/threats/cve-2026-55778-parse-server-stored-xss-via-file-upload-extension-bypass)
- [Parse Server supply chain compromise via unreviewed version tags](https://junglewise.ai/threats/cve-2021-47986-parse-server-supply-chain-compromise-via-unreviewed-version-tags)