CVE-2026-32728 Parse Server has a stored XSS filter bypass via Content-Type MIME parameter and missing XML extension blocklist entries

What is CVE-2026-32728?

CVE-2026-32728 is a high-severity cross-site scripting vulnerability in Parseplatform Parse-Server, published on 18 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.6.0-alpha.15 and 8.6.41, 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. The fix in versions 9.6.0-alpha.15 and 8.6.41 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. As a workaround, 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.

Weakness: CWE-79

Which versions are affected by CVE-2026-32728?

5 open source packages ship an affected version, including parse-server and parse. It affects 1 product.

Products include Parseplatform Parse-Server.

How do I fix CVE-2026-32728?

Upgrade parse-server to a fixed version for your release line: 8.6.41 or 9.6.0-alpha.15.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-32728 being exploited?

There is no known exploitation of CVE-2026-32728 in the wild and no public exploit code.

Other vulnerabilities in Parseplatform Parse-Server

• CVE-2026-30966 Parse Server role escalation and CLP bypass via direct `_Join` table write Critical 10.0
• CVE-2024-27298 Parse Server literalizeRegexPart SQL Injection Critical 10.0
• CVE-2022-24760 Command Injection in Parse server Critical 10.0
• CVE-2026-30965 Parse Server session token exfiltration via `redirectClassNameForKey` query parameter Critical 9.9
• CVE-2023-36475 Parse Server vulnerable to remote code execution via MongoDB BSON parser through prototype pollution Critical 9.8

All Parseplatform Parse-Server vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-parse-2026-32728, GHSA-42ph-pf9q-cr72.