#VU116912 Incorrect Regular Expression in Sinatra - CVE-2025-61921
Published: October 13, 2025
Vulnerability identifier: #VU116912
Vulnerability risk: Medium
CVSSv4.0: 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/E:U/U:Green
CVE-ID: CVE-2025-61921
CWE-ID: CWE-185
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Sinatra
Sinatra
Software vendor:
Sinatra
Sinatra
Description
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to insufficient input validation when processing regular expressions in ETag generation within the If-Match and If-None-Match header parsing component. A remote attacker can pass specially crafted data to the application and perform regular expression denial of service (ReDos) attack.
Remediation
Install updates from vendor's website.