CVE-2026-61448: Parse Server stored XSS via malformed Content-Type bypass

CVE-2026-61448 · Severity: medium · CVSS 4 · Published 2026-07-11

Parse Server, an open-source backend framework, is vulnerable to a security flaw that allows users to upload malicious files. By using a specially crafted file type, an attacker can bypass security filters and store a file that acts as a script. If another user opens this file, the script will run in their browser, potentially allowing the attacker to steal session information or perform actions on the user's behalf.

Technologies: parse-server (npm). Vendors: npm.

Quick answers

Is CVE-2026-61448 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-61448 being exploited in the wild.
How severe is CVE-2026-61448?
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,fixed=9.10.0-alpha.2.
Is there a fix for CVE-2026-61448?
Yes. parse-server (npm): upgrade to 9.10.0-alpha.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-61448 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-61448?
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.

How to fix

  • parse-server (npm): upgrade to 9.10.0-alpha.2 or later
    npm install parse-server@9.10.0-alpha.2

Technical details

A stored cross-site scripting (XSS) vulnerability exists in Parse Server due to improper validation of client-supplied Content-Type headers. When a file extension is not recognized by the 'mime' package, the server preserves the client-provided Content-Type. Attackers can provide malformed types (e.g., 'image//svg+xml') that bypass the 'fileUpload.fileExtensions' blocklist. When these files are served from adapters like Amazon S3, Google Cloud Storage, or Azure Blob Storage, browsers may fail to parse the header and resort to MIME-sniffing. If the file content begins with HTML, it is executed in the application's origin. The default GridFS adapter is unaffected as it recomputes Content-Type and uses 'nosniff' headers. Fixes are available in versions 9.10.0-alpha.2 and 8.6.84.

Affected products

  • parse-community Parse Server >= 9.0.0, < 9.10.0-alpha.2; <= 8.6.83

Identifiers

  • CVE-2026-61448
  • BIT-PARSE-2026-61448
  • GHSA-r899-h629-j84r

Timeline

  • 2026-06-25: advisory: GitHub advisory published by maintainers
  • 2026-07-11: disclosed: NVD publication date

References

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