VULNERABILITY INTELLIGENCE

CVE-2021-21317

CVSS score5.3 MEDIUM

EPSS probability2.52%

CISA KEVNot currently listed

Published2021-02-16

Last modified2026-06-17

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Description

uap-core in an open-source npm package which contains the core of BrowserScope's original user agent string parser. In uap-core before version 0.11.0, some regexes are vulnerable to regular expression denial of service (REDoS) due to overlapping capture groups. This allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to maliciously crafted long strings. This is fixed in version 0.11.0. Downstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.

Weakness classification

security-advisories@github.com: CWE-400
nvd@nist.gov: CWE-1333

Primary references

security-advisories@github.com — Patch
security-advisories@github.com — Third Party Advisory
security-advisories@github.com — Product, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Patch
af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Product, Third Party Advisory