CVE-2018-20164: Uaparser User Agent Parser-Core

Medium severity, CVSS 5.3. EPSS: 3.3% chance of exploitation in the next 30 days.

An issue was discovered in regex.yaml (aka regexes.yaml) in UA-Parser UAP-Core before 0.6.0. A Regular Expression Denial of Service (ReDoS) issue allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to a value containing a long digit string. (The UAP-Core project contains the vulnerability, propagating to all implementations.)

Affected products

• Uaparser User Agent Parser-Core: before 0.6.0 (fixed in 0.6.0)

Published 2019-02-13. Last modified 2026-06-17.