{"id":"CVE-2020-5243","aliases":["DEBIAN-CVE-2020-5243","EUVD-2020-0301","GHSA-cmcx-xhr8-3w9p","UBUNTU-CVE-2020-5243"],"status":"published","title":"Denial of Service in uap-core when processing crafted User-Agent strings","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","severity":{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.02289,"percentile":0.83348,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1333","CWE-20"],"published":"2020-02-20T23:15:14Z","modified":"2026-10-26T12:02:03Z","fixes":[{"ecosystem":"npm","package":"uap-core","fixed_in":["0.7.3"],"sources":["ghsa","osv"]},{"ecosystem":"RubyGems","package":"user_agent_parser","fixed_in":["2.6.0"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:12","package":"uap-core","fixed_in":["1:0.8.0-1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"uap-core","fixed_in":["1:0.8.0-1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"uap-core","fixed_in":["1:0.8.0-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.7.3"}]}]},{"source":"ghsa","ecosystem":"RubyGems","package":"user_agent_parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.6.0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:0.8.0-1"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:0.8.0-1"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"uap-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:0.8.0-1"}]}]},{"source":"osv","ecosystem":"npm","package":"uap-core","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.7.3"}]}]},{"source":"osv","ecosystem":"RubyGems","package":"user_agent_parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.6.0"}]}],"versions":["0.1.0","0.1.1","0.1.2","1.0.0","1.0.1","1.0.2","2.0.0","2.1.0","2.1.1","2.1.2","2.1.3","2.1.4","2.1.5","2.2.0","2.3.0","2.3.1","2.3.2","2.4.0","2.4.1","2.5.0","2.5.1","2.5.2","2.5.3"]},{"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-cmcx-xhr8-3w9p","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Third Party Advisory","evidence","web","report"]},{"url":"https://github.com/ua-parser/uap-core/commit/0afd61ed85396a3b5316f18bfd1edfaadf8e88e1","tags":["x_refsource_MISC","x_transferred","Patch","fix","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-5243","tags":["advisory"]},{"url":"https://github.com/ua-parser/uap-ruby/security/advisories/GHSA-pcqq-5962-hvcw","tags":["web"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/user_agent_parser/CVE-2020-5243.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-cmcx-xhr8-3w9p"},{"url":"https://security-tracker.debian.org/tracker/CVE-2020-5243","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2020-5243","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2020-5243","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2020-5243","title":"Denial of Service in uap-core when processing crafted User-Agent strings","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","status":"published","published":"2020-02-20T23:15:14Z","modified":"2024-08-04T08:22:09.077Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:35:47.56691Z"}],"euvd":[{"id":"EUVD-2020-0301","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","status":"published","published":"2020-02-20T23:15:14Z","modified":"2024-08-04T08:22:09Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T03:08:07.28588Z"}],"ghsa":[{"id":"GHSA-cmcx-xhr8-3w9p","title":"Denial of Service in uap-core when processing crafted User-Agent strings","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 \u0026amp;amp;gt;= v0.7.3\n\nDownstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.\n\n### Details\n\nEach vulnerable regular expression reported here contains 3 overlapping capture groups. Backtracking has approximately cubic time complexity with respect to the length of the user-agent string.\n\n#### Regex 1:\n\n```\n\\bSmartWatch *\\( *([^;]+) *; *([^;]+) *;\n```\n\nis vulnerable in portion ` *([^;]+) *` and can be attacked with\n\n```python\n\u0026amp;amp;quot;SmartWatch(\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\ne.g.\n```\nSmartWatch(                                   z\n```\n\n\n#### Regex 2:\n\n```\n; *([^;/]+) Build[/ ]Huawei(MT1-U06|[A-Z]+\\d+[^\\);]+)[^\\);]*\\)\n```\n\nis vulnerable in portion `\\d+[^\\);]+[^\\);]*` and can be attacked with\n\n```python\n\u0026amp;amp;quot;;A Build HuaweiA\u0026amp;amp;quot; + (\u0026amp;amp;quot;4\u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\n\n\n#### Regex 3:\n\n```\n(HbbTV)/[0-9]+\\.[0-9]+\\.[0-9]+ \\([^;]*; *(LG)E *; *([^;]*) *;[^;]*;[^;]*;\\)\n```\n\nis vulnerable in portion ` *([^;]*) *` and can be attacked with\n\n```python\n\u0026amp;amp;quot;HbbTV/0.0.0 (;LGE;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\n\n#### Regex 4:\n\n```\n(HbbTV)/[0-9]+\\.[0-9]+\\.[0-9]+ \\([^;]*; *(?:CUS:([^;]*)|([^;]+)) *; *([^;]*) *;.*;\n```\n\nis vulnerable in portions ` *(?:CUS:([^;]*)|([^;]+)) *` and ` *([^;]*) *` and can be attacked with\n\n```python\n\u0026amp;amp;quot;HbbTV/0.0.0 (;CUS:;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n\u0026amp;amp;quot;HbbTV/0.0.0 (;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n\u0026amp;amp;quot;HbbTV/0.0.0 (;z;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\n\nReported by Ben Caller @bcaller","status":"published","published":"2020-02-20T23:26:10Z","modified":"2024-02-08T22:49:51Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-20","CWE-1333"],"updated_at":"2026-11-02T14:37:36.777238Z"}],"nvd":[{"id":"CVE-2020-5243","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","status":"published","published":"2020-02-21T00:15:10.96Z","modified":"2026-06-17T03:21:07.01Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"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","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-20","CWE-1333"],"updated_at":"2026-11-02T14:05:54.796125Z"}],"osv":[{"id":"CVE-2020-5243","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","status":"published","published":"2020-02-21T00:15:10.96Z","modified":"2026-10-20T10:53:28.457374003Z","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"}],"updated_at":"2026-11-02T15:44:16.936975Z"},{"id":"DEBIAN-CVE-2020-5243","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","status":"published","published":"2020-02-21T00:15:10.96Z","modified":"2026-10-26T12:02:03.970591666Z","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"}],"updated_at":"2026-11-02T15:45:34.019707Z"},{"id":"GHSA-cmcx-xhr8-3w9p","title":"Denial of Service in uap-core when processing crafted User-Agent strings","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 \u0026amp;amp;gt;= v0.7.3\n\nDownstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.\n\n### Details\n\nEach vulnerable regular expression reported here contains 3 overlapping capture groups. Backtracking has approximately cubic time complexity with respect to the length of the user-agent string.\n\n#### Regex 1:\n\n```\n\\bSmartWatch *\\( *([^;]+) *; *([^;]+) *;\n```\n\nis vulnerable in portion ` *([^;]+) *` and can be attacked with\n\n```python\n\u0026amp;amp;quot;SmartWatch(\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\ne.g.\n```\nSmartWatch(                                   z\n```\n\n\n#### Regex 2:\n\n```\n; *([^;/]+) Build[/ ]Huawei(MT1-U06|[A-Z]+\\d+[^\\);]+)[^\\);]*\\)\n```\n\nis vulnerable in portion `\\d+[^\\);]+[^\\);]*` and can be attacked with\n\n```python\n\u0026amp;amp;quot;;A Build HuaweiA\u0026amp;amp;quot; + (\u0026amp;amp;quot;4\u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\n\n\n#### Regex 3:\n\n```\n(HbbTV)/[0-9]+\\.[0-9]+\\.[0-9]+ \\([^;]*; *(LG)E *; *([^;]*) *;[^;]*;[^;]*;\\)\n```\n\nis vulnerable in portion ` *([^;]*) *` and can be attacked with\n\n```python\n\u0026amp;amp;quot;HbbTV/0.0.0 (;LGE;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\n\n#### Regex 4:\n\n```\n(HbbTV)/[0-9]+\\.[0-9]+\\.[0-9]+ \\([^;]*; *(?:CUS:([^;]*)|([^;]+)) *; *([^;]*) *;.*;\n```\n\nis vulnerable in portions ` *(?:CUS:([^;]*)|([^;]+)) *` and ` *([^;]*) *` and can be attacked with\n\n```python\n\u0026amp;amp;quot;HbbTV/0.0.0 (;CUS:;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n\u0026amp;amp;quot;HbbTV/0.0.0 (;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n\u0026amp;amp;quot;HbbTV/0.0.0 (;z;\u0026amp;amp;quot; + (\u0026amp;amp;quot; \u0026amp;amp;quot; * 3500) + \u0026amp;amp;quot;z\u0026amp;amp;quot;\n```\n\nReported by Ben Caller @bcaller","status":"published","published":"2020-02-20T23:26:10Z","modified":"2026-07-08T06:27:49.976052814Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-1333","CWE-20"],"updated_at":"2026-11-02T15:46:45.28161Z"},{"id":"UBUNTU-CVE-2020-5243","description":"uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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 has been patched in uap-core 0.7.3.","status":"published","published":"2020-02-21T00:15:00Z","modified":"2026-10-17T12:56:14.611235722Z","cvss":[{"version":"3.1","score":5.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","level":"medium"},{"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"}],"updated_at":"2026-11-02T15:54:25.179924Z"}]}}