CVE-2026-32728

Workarounds

Configure the fileUpload.fileExtensions option to use an allowlist of only the file extensions that your application needs, rather than relying on the default blocklist.

An attacker who is allowed to upload files can bypass the file extension filter by appending a MIME parameter (e.g. ;charset=utf-8) to the Content-Type header. This causes the extension validation to fail matching against the blocklist, allowing active content to be stored and served under the application's domain. In addition, certain XML-based file extensions that can render scripts in web browsers are not included in the default blocklist.

This can lead to stored XSS attacks, compromising session tokens, user credentials, or other sensitive data accessible via the browser's local storage.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

The fix strips MIME parameters from the Content-Type header before validating the file extension against the blocklist. The default blocklist has also been extended to include additional XML-based extensions (xsd, rng, rdf, rdf+xml, owl, mathml, mathml+xml) that can render active content in web browsers.

Note that the fileUpload.fileExtensions option is intended to be configured as an allowlist of file extensions that are valid for a specific application, not as a denylist. The default denylist is provided only as a basic default that covers most common problematic extensions. It is not intended to be an exhaustive list of all potentially dangerous extensions. Developers should not rely on the default value, as new extensions that can render active content in browsers might emerge in the future.

1. What is CVE-2026-32728? CVE-2026-32728 is a high-severity cross-site scripting (XSS) vulnerability in parse-server (npm), affecting versions >= 9.0.0, < 9.6.0-alpha.15. It is fixed in 9.6.0-alpha.15, 8.6.41. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which versions of parse-server are affected by CVE-2026-32728? parse-server (npm) versions >= 9.0.0, < 9.6.0-alpha.15 is affected.
3. Is there a fix for CVE-2026-32728? Yes. CVE-2026-32728 is fixed in 9.6.0-alpha.15, 8.6.41. Upgrade to this version or later.
4. Is CVE-2026-32728 exploitable, and should I be worried? Whether CVE-2026-32728 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-32728 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-32728?
   • Upgrade parse-server to 9.6.0-alpha.15 or later
   • Upgrade parse-server to 8.6.41 or later

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