Inefficient regular expression complexity in parse-server - CVE-2026-47138
Published: May 23, 2026
Vulnerability identifier: #VU132207
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-47138
CWE-ID: CWE-1333
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient regular expression complexity in the request-header parser when processing the client SDK version field on /parse/* requests. A remote attacker can send a single specially crafted HTTP request to cause a denial of service.
The issue is reachable before session authentication and before rate limiting, and the X-Parse-Client-Version header or _ClientVersion JSON body field can trigger prolonged synchronous CPU consumption on a Node.js worker. Production deployments running the default configuration are affected.
Affected software
parse-server
How to mitigate CVE-2026-47138
Install security update from vendor's website.
parse-server - addressed in versions 8.6.77, 9.9.1 alpha.1