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.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-42ph-pf9q-cr72 Parse Server has a stored XSS filter bypass via Content-Type MIME parameter and missing XML extension blocklist entries
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 19 Mar 2026 09:45:00 +0000

Type Values Removed Values Added
First Time appeared Parse Community
Parse Community parse Server
Vendors & Products Parse Community
Parse Community parse Server

Wed, 18 Mar 2026 22:00:00 +0000

Type Values Removed Values Added
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.
Title Parse Server has a stored XSS filter bypass via Content-Type MIME parameter and missing XML extension blocklist entries
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 8.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-18T21:31:08.506Z

Reserved: 2026-03-13T15:02:00.626Z

Link: CVE-2026-32728

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-18T22:16:24.983

Modified: 2026-03-18T22:16:24.983

Link: CVE-2026-32728

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-03-19T08:55:24Z

Weaknesses