Vulnerability · Published Feb 16, 2021 · Assigned by GitHub_M

CVE-2021-21317Denial of Service in uap-core

Medium 5.3

In plain English

A medium-severity uncontrolled resource consumption in uap-core from ua-parser. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.5% (higher than 85% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)2.5%top 15.1% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Ubuntu:22.04:LTS	uap-core	no fix listed	UBUNTU-CVE-2021-21317
Ubuntu:24.04:LTS	uap-core	no fix listed	UBUNTU-CVE-2021-21317
Ubuntu:25.10	uap-core	no fix listed	UBUNTU-CVE-2021-21317
Ubuntu:26.04:LTS	uap-core	no fix listed	UBUNTU-CVE-2021-21317
Ubuntu:26.10	uap-core	no fix listed	UBUNTU-CVE-2021-21317
npm	uap-core	0.11.0	GHSA-p4pj-mg4r-x6v4

Affected products (as reported)

Vendor	Product	Versions
ua-parser	uap-core	< 0.11.0

Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

https://github.com/ua-parser/uap-core/security/advisories/GHSA-p4pj-mg4r-x6v4 x_refsource_CONFIRM
https://github.com/ua-parser/uap-core/commit/dc9925d458214cfe87b93e35346980612f6ae96c x_refsource_MISC
https://www.npmjs.com/package/uap-core x_refsource_MISC