{"cve":"CVE-2021-21317","nvd":{"published":"2021-02-16T18:15:12.583","modified":"2026-06-17T03:35:17.093","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-1333","CWE-400"],"references":["https://github.com/ua-parser/uap-core/commit/dc9925d458214cfe87b93e35346980612f6ae96c","https://github.com/ua-parser/uap-core/security/advisories/GHSA-p4pj-mg4r-x6v4","https://www.npmjs.com/package/uap-core","https://github.com/ua-parser/uap-core/commit/dc9925d458214cfe87b93e35346980612f6ae96c","https://github.com/ua-parser/uap-core/security/advisories/GHSA-p4pj-mg4r-x6v4"],"products":["uap-core_project:uap-core"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-21317","score":0.02517,"percentile":0.84826,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-p4pj-mg4r-x6v4","url":"https://osv.dev/vulnerability/GHSA-p4pj-mg4r-x6v4","summary":"Denial of Service in uap-core","modified":"2026-07-08T06:27:33.229785880Z","packages":[{"ecosystem":"npm","name":"uap-core","purl":"pkg:npm/uap-core","ranges":["<0.11.0"],"fixed":["0.11.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}