{"id":"CVE-2023-22465","aliases":["EUVD-2023-0335","GHSA-54w6-vxfh-fw7f"],"status":"published","title":"Http4s has fatal error parsing User-Agent and Server headers","description":"Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.","severity":{"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":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00886,"percentile":0.59566,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-20"],"published":"2023-01-04T15:30:04Z","modified":"2026-10-28T02:30:45Z","fixes":[{"ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","fixed_in":["0.21.34","0.22.15","0.23.17","1.0.0-M38"],"sources":["ghsa","osv"]},{"ecosystem":"Maven","package":"org.http4s:http4s-core_2.12","fixed_in":["0.21.34","0.22.15","0.23.17"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"fixed":"0.21.34"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.22.0"},{"fixed":"0.22.15"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.23.0"},{"fixed":"0.23.17"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"fixed":"1.0.0-M38"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.10","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"last_affected":"0.9.3"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.11","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"last_affected":"0.21.0-M1"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"fixed":"0.21.34"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.22.0"},{"fixed":"0.22.15"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.23.0"},{"fixed":"0.23.17"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"last_affected":"1.0.0-M30"}]}]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"fixed":"0.21.34"}]}],"versions":["0.10.0-M10","0.21.0","0.21.0-M1","0.21.0-M2","0.21.0-M3","0.21.0-M4","0.21.0-M5","0.21.0-M6","0.21.0-RC1","0.21.0-RC2","0.21.0-RC3","0.21.0-RC4","0.21.0-RC5","0.21.1","0.21.11","0.21.12","0.21.13","0.21.14","0.21.15","0.21.16","0.21.17","0.21.18","0.21.19","0.21.2","0.21.20","0.21.21","0.21.22","0.21.23","0.21.24","0.21.25","0.21.26","0.21.27","0.21.28","0.21.29","0.21.3","0.21.30","0.21.31","0.21.32","0.21.33","0.21.4","0.21.5","0.21.6","0.21.7","0.21.8","0.21.9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.22.0"},{"fixed":"0.22.15"}]}],"versions":["0.22-129-24d065b","0.22-143-49b5a8d","0.22-53-01128f5","0.22-96-55d3184","0.22.0","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.23.0"},{"fixed":"0.23.17"}]}],"versions":["0.23.0","0.23.1","0.23.10","0.23.11","0.23.12","0.23.13","0.23.14","0.23.15","0.23.16","0.23.2","0.23.3","0.23.4","0.23.5","0.23.6","0.23.7","0.23.8","0.23.9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"fixed":"1.0.0-M38"}]}],"versions":["1.0.0-M10","1.0.0-M11","1.0.0-M13","1.0.0-M14","1.0.0-M15","1.0.0-M16","1.0.0-M17","1.0.0-M18","1.0.0-M19","1.0.0-M2","1.0.0-M20","1.0.0-M21","1.0.0-M22","1.0.0-M23","1.0.0-M24","1.0.0-M25","1.0.0-M27","1.0.0-M28","1.0.0-M29","1.0.0-M3","1.0.0-M30","1.0.0-M31","1.0.0-M32","1.0.0-M33","1.0.0-M34","1.0.0-M35","1.0.0-M36","1.0.0-M37","1.0.0-M4","1.0.0-M5","1.0.0-M6","1.0.0-M7","1.0.0-M8","1.0.0-M9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core_2.10","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"last_affected":"0.9.3"}]}],"versions":["0.1.0","0.2.0","0.3.0","0.4.0","0.4.1","0.4.2","0.5.0","0.5.1","0.5.2","0.5.3","0.5.4","0.6.0","0.6.1","0.6.2","0.6.3","0.6.4","0.6.5","0.7.0","0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.8.5","0.8.6","0.9.0","0.9.1","0.9.2","0.9.3"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core_2.11","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"last_affected":"0.21.0-M1"}]}],"versions":["0.10.0","0.10.1","0.11.0","0.11.1","0.11.2","0.11.3","0.12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0.23.9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"last_affected":"1.0.0-M30"}]}]}],"products":[{"vendor":"http4s","product":"http4s"},{"vendor":"typelevel","product":"http4s"}],"references":[{"url":"https://github.com/http4s/http4s/security/advisories/GHSA-54w6-vxfh-fw7f","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Mitigation","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-22465","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-54w6-vxfh-fw7f"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/22xxx/CVE-2023-22465.json","tags":["advisory"]},{"url":"https://github.com/http4s/http4s","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2023-22465","title":"Http4s has fatal error parsing User-Agent and Server headers","description":"Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.","status":"published","published":"2023-01-04T15:30:04.129Z","modified":"2025-03-10T21:32:44.734Z","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","assessor":"cna"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:35:15.779187Z"}],"euvd":[{"id":"EUVD-2023-0335","description":"Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.","status":"published","published":"2023-01-04T15:30:04Z","modified":"2025-03-10T21:32:44Z","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":"2026-11-02T20:53:08.584552Z"}],"ghsa":[{"id":"GHSA-54w6-vxfh-fw7f","title":"Http4s improperly parses User-Agent and Server headers","description":"### Impact\n\nThe `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. \n\n#### v0.21.x\n\n```scala\nval unsafe: Option[`User-Agent`] = req.headers.get(`User-Agent`)\n```\n\n#### v0.22.x, v0.23.x, v1.x\n\n```scala\nval unsafe: Option[`User-Agent`] = req.headers.get[`User-Agent`]\nval alsoUnsafe: Option[`Server`] = req.headers.get[Server]\n```\n\n### Patches\n\nFixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38.\n\n### Workarounds\n\n#### Use the weakly typed header interface\n\n##### v0.21.x\n\n```scala\nval safe: Option[Header] = req.headers.get(\"User-Agent\".ci)\n// but don't do this\nval unsafe = header.map(_.parsed) \n```\n\n##### v0.22.x, v0.23.x, v1.x\n\n```scala\nval safe: Option[Header] = req.headers.get(ci\"User-Agent\")\n```","status":"published","published":"2023-01-06T20:24:36Z","modified":"2025-12-11T20:58:48Z","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-20"],"updated_at":"2026-11-02T14:39:12.222121Z"}],"nvd":[{"id":"CVE-2023-22465","description":"Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.","status":"published","published":"2023-01-04T16:15:09.323Z","modified":"2026-06-17T05:35:30.8Z","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","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"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:07:45.305824Z"}],"osv":[{"id":"CVE-2023-22465","title":"Http4s has fatal error parsing User-Agent and Server headers","description":"Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.","status":"published","published":"2023-01-04T15:30:04.129Z","modified":"2026-10-28T02:30:45.865179468Z","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-20"],"updated_at":"2026-11-02T15:44:30.334753Z"},{"id":"GHSA-54w6-vxfh-fw7f","title":"Http4s improperly parses User-Agent and Server headers","description":"### Impact\n\nThe `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. \n\n#### v0.21.x\n\n```scala\nval unsafe: Option[`User-Agent`] = req.headers.get(`User-Agent`)\n```\n\n#### v0.22.x, v0.23.x, v1.x\n\n```scala\nval unsafe: Option[`User-Agent`] = req.headers.get[`User-Agent`]\nval alsoUnsafe: Option[`Server`] = req.headers.get[Server]\n```\n\n### Patches\n\nFixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38.\n\n### Workarounds\n\n#### Use the weakly typed header interface\n\n##### v0.21.x\n\n```scala\nval safe: Option[Header] = req.headers.get(\"User-Agent\".ci)\n// but don't do this\nval unsafe = header.map(_.parsed) \n```\n\n##### v0.22.x, v0.23.x, v1.x\n\n```scala\nval safe: Option[Header] = req.headers.get(ci\"User-Agent\")\n```","status":"published","published":"2023-01-06T20:24:36Z","modified":"2025-12-11T21:03:44.483986Z","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-20"],"updated_at":"2026-11-02T15:46:37.864461Z"}]}}