CVE-2021-21317

Publication date 16 February 2021

Last updated 11 July 2025

Ubuntu priority

Cvss 3 Severity Score

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
uap-core	26.04 LTS resolute	Vulnerable
	25.10 questing	Ignored end of life, was needed
	25.04 plucky	Ignored end of life, was needed
	24.10 oracular	Ignored end of life, was needed
	24.04 LTS noble	Vulnerable
	23.10 mantic	Ignored end of life, was needed
	23.04 lunar	Ignored end of life, was needed
	22.10 kinetic	Ignored end of life, was needed
	22.04 LTS jammy	Vulnerable
	21.10 impish	Ignored end of life
	21.04 hirsute	Ignored end of life
	20.10 groovy	Ignored end of life
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
uap-core	Upstream: dc9925d

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.3 · Medium

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	Low

Scores

Parameter	Value
Base score	5.3 · Medium
Exploitability score	-
Impact score	-

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