Arbitrary file upload in Parse-Community Parse-Server

CVE-2026-55778

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81.

Vulnerability class: Unrestricted File Upload

EPSS: 0.004 (34.1th percentile) — read the EPSS interpretation.

Affected products

Weakness classification (CWE)

References