Arbitrary file upload in Parse Server - CVE-2026-55778
Published: June 30, 2026
Vulnerability identifier: #VU135970
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-55778
CWE-ID: CWE-434
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to perform stored cross-site scripting.
The vulnerability exists due to unrestricted upload of file with dangerous type in the file upload extension validation in Parse Server when uploading a file with a non-standard or compound extension together with a dangerous content type. A remote user can upload a specially crafted file to perform stored cross-site scripting.
Exploitation requires a storage adapter that persists and serves the uploaded content type, such as S3 or GCS, and a victim must open the uploaded file URL.
Affected software
Parse Server
How to mitigate CVE-2026-55778
Install security update from vendor's website.
Parse Server - addressed in versions 8.6.81, 9.9.1 alpha.11