Description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.79 and 9.9.1-alpha.4, the default file upload extension blocklist can be bypassed by appending a trailing dot to a filename whose extension would otherwise be blocked (e.g. poc.svg.). The trailing dot causes the extension parser to extract an empty string, which short-circuits the blocklist check, and the attacker-controlled Content-Type is forwarded to the storage adapter unchanged. Storage adapters that persist and serve the provided Content-Type (such as S3 or GCS) then serve the file with an active type such as image/svg+xml, enabling stored XSS when a victim opens the file URL. The default GridFS adapter is not affected because it sets X-Content-Type-Options: nosniff on responses. This issue has been patched in versions 8.6.79 and 9.9.1-alpha.4.
Problem types
CWE-434: Unrestricted Upload of File with Dangerous Type
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Product status
>= 9.0.0, < 9.9.1-alpha.4
References
github.com/...server/security/advisories/GHSA-7wqv-xjf3-x35v
github.com/parse-community/parse-server/pull/10489
github.com/parse-community/parse-server/pull/10490