{"id":"CVE-2021-21317","aliases":["EUVD-2021-0561","GHSA-p4pj-mg4r-x6v4","UBUNTU-CVE-2021-21317"],"status":"published","title":"Denial of Service in uap-core","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.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.02548,"percentile":0.85245,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1333","CWE-400"],"published":"2021-02-02T15:46:38Z","modified":"2026-10-20T10:54:28Z","fixes":[{"ecosystem":"npm","package":"uap-core","fixed_in":["0.11.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.11.0"}]}]},{"source":"osv","ecosystem":"npm","package":"uap-core","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.11.0"}]}]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["20190213-2"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:0.12.0-1","1:0.13.0-1","1:0.14.0-1","1:0.15.0-1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:0.18.0-1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:0.18.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:0.18.0-1build1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:0.18.0-1","1:0.18.0-1build1"]}],"products":[{"vendor":"ua-parser","product":"uap-core"},{"vendor":"uap-core_project","product":"uap-core"}],"references":[{"url":"https://github.com/ua-parser/uap-core/security/advisories/GHSA-p4pj-mg4r-x6v4","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory","web","report"]},{"url":"https://github.com/ua-parser/uap-core/commit/dc9925d458214cfe87b93e35346980612f6ae96c","tags":["x_refsource_MISC","x_transferred","Patch","fix","web"]},{"url":"https://www.npmjs.com/package/uap-core","tags":["x_refsource_MISC","x_transferred","Product","Third Party Advisory","advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21317","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-p4pj-mg4r-x6v4"},{"url":"https://github.com/ua-parser/uap-core","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2021-21317","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-21317","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2021-21317","title":"Denial of Service in uap-core","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":"published","published":"2021-02-16T17:45:16Z","modified":"2024-08-03T18:09:15.054Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:33:00.137099Z"}],"euvd":[{"id":"EUVD-2021-0561","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":"published","published":"2021-02-16T17:45:16Z","modified":"2024-08-03T18:09:15Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-03T03:25:06.913643Z"}],"ghsa":[{"id":"GHSA-p4pj-mg4r-x6v4","title":"Denial of Service in uap-core","description":"## Impact\n\nSome 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.\n\n## Patches\n\nPlease update uap-core to \u003e= v0.11.0\n\nDownstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.","status":"published","published":"2021-02-02T15:46:38Z","modified":"2024-02-08T22:17:20Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-1333"],"updated_at":"2026-11-02T14:37:36.777238Z"}],"nvd":[{"id":"CVE-2021-21317","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":"published","published":"2021-02-16T18:15:12.583Z","modified":"2026-06-17T03:35:17.093Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-400","CWE-1333"],"updated_at":"2026-11-02T14:06:50.031227Z"}],"osv":[{"id":"CVE-2021-21317","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":"published","published":"2021-02-16T18:15:12.583Z","modified":"2026-10-20T10:54:28.067000016Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-02T15:44:18.004149Z"},{"id":"GHSA-p4pj-mg4r-x6v4","title":"Denial of Service in uap-core","description":"## Impact\n\nSome 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.\n\n## Patches\n\nPlease update uap-core to \u003e= v0.11.0\n\nDownstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.","status":"published","published":"2021-02-02T15:46:38Z","modified":"2026-07-08T06:27:33.22978588Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-1333","CWE-400"],"updated_at":"2026-11-02T15:46:52.534897Z"},{"id":"UBUNTU-CVE-2021-21317","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":"published","published":"2021-02-16T18:15:00Z","modified":"2026-10-17T12:56:19.36575543Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-02T15:54:26.29421Z"}]}}