Name: CVE-2021-21317: Uncontrolled Resource Consumption
Creator: Rapid7
Published: 2021-02-16T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2021-21317, CWE-400, CWE-1333, CVSS 5.3, EPSS 0.02517

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.

CVSS Details

CVSS 3.1 Base Score: 5.3
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Ubuntu	—	No solution exists	Jun 26, 2025	Feb 16, 2021

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CVSS Details

Covered by Rapid7

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