{"id":"CVE-2026-69205","aliases":["EUVD-2026-79190","GHSA-9998-894r-fwvr"],"status":"published","title":"Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","severity":{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.0048,"percentile":0.41679,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-444"],"published":"2026-09-15T19:15:21Z","modified":"2026-10-28T02:30:22Z","fixes":[{"ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","fixed_in":["0.23.35","1.0.0-M47"],"sources":["ghsa","osv"]},{"ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","fixed_in":["0.23.35","1.0.0-M47"],"sources":["ghsa","osv"]},{"ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.12","fixed_in":["0.23.35"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.23.34"},{"fixed":"0.23.35"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.23.34"},{"fixed":"0.23.35"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.23.34"},{"fixed":"0.23.35"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"last_affected":"1.0.0-M46"},{"fixed":"1.0.0-M47"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"last_affected":"1.0.0-M46"},{"fixed":"1.0.0-M47"}]}]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.35"}]}],"versions":["0.22.0","0.22.0-M8","0.22.0-RC1","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.15","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9","0.23.0","0.23.0-M1","0.23.0-RC1","0.23.1","0.23.10","0.23.11","0.23.12","0.23.13","0.23.14","0.23.15","0.23.16","0.23.17","0.23.18","0.23.19","0.23.19-RC1","0.23.19-RC2","0.23.19-RC3","0.23.2","0.23.20","0.23.21","0.23.22","0.23.23","0.23.24","0.23.25","0.23.26","0.23.27","0.23.28","0.23.29","0.23.3","0.23.30","0.23.31","0.23.32","0.23.33","0.23.34","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-ember-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.35"}]}],"versions":["0.10.0-M10","0.21.0","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","0.21.34","0.21.4","0.21.5","0.21.6","0.21.7","0.21.8","0.21.9","0.22-129-24d065b","0.22-143-49b5a8d","0.22-53-01128f5","0.22-96-55d3184","0.22.0","0.22.0-M1","0.22.0-M2","0.22.0-M3","0.22.0-M4","0.22.0-M5","0.22.0-M6","0.22.0-M7","0.22.0-M8","0.22.0-RC1","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.15","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9","0.23.0","0.23.0-M1","0.23.0-RC1","0.23.1","0.23.10","0.23.11","0.23.12","0.23.13","0.23.14","0.23.15","0.23.16","0.23.17","0.23.18","0.23.19","0.23.19-RC1","0.23.19-RC2","0.23.19-RC3","0.23.2","0.23.20","0.23.21","0.23.22","0.23.23","0.23.24","0.23.25","0.23.26","0.23.27","0.23.28","0.23.29","0.23.3","0.23.30","0.23.31","0.23.32","0.23.33","0.23.34","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-ember-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.35"}]}],"versions":["0.10.0-M10","0.21.0","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","0.21.34","0.21.4","0.21.5","0.21.6","0.21.7","0.21.8","0.21.9","0.22-129-24d065b","0.22-143-49b5a8d","0.22-53-01128f5","0.22-96-55d3184","0.22.0","0.22.0-M1","0.22.0-M2","0.22.0-M3","0.22.0-M4","0.22.0-M5","0.22.0-M6","0.22.0-M7","0.22.0-M8","0.22.0-RC1","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.15","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9","0.23.0","0.23.0-M1","0.23.0-RC1","0.23.1","0.23.10","0.23.11","0.23.12","0.23.13"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Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:15:21.235Z","modified":"2026-09-15T19:33:09.007Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T13:50:16.178634Z"}],"euvd":[{"id":"EUVD-2026-79190","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:15:21Z","modified":"2026-09-15T19:33:09Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T17:28:16.983725Z"}],"ghsa":[{"id":"GHSA-9998-894r-fwvr","title":"Http4s Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)","description":"## Summary\n\nEmber's HTTP/1.1 header parser matches the `Transfer-Encoding` header value\nwith a case-sensitive substring test (`hValue.contains(\"chunked\")`). RFC\n9112 §7 requires transfer-coding names to be compared case-insensitively. A\nrequest carrying `Transfer-Encoding: Chunked` (capital C) is therefore not\nrecognised as chunked, and Ember falls back to framing by `Content-Length`\n(or zero if absent) while a compliant intermediary frames the same bytes by\nchunked encoding. The two parsers then disagree on where the request body\nends, enabling HTTP request smuggling (TE.CL / TE.0).\n\nThe same line of code admits two further variants:\n\n- The substring test misfires on `Transfer-Encoding: notchunked` (an inverse\n  desync — Ember treats it as chunked while a compliant intermediary\n  rejects the unknown coding).\n- Header field bytes are decoded with the platform-default charset. Under\n  UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which\n  `String.equalsIgnoreCase` Unicode-case-folds to `k`, so\n  `Transfer-Encoding: chun\u003cU+212A\u003eed` matches `chunked` once the comparison\n  is made case-insensitive without also pinning the decode to ISO-8859-1.\n\n## Impact\n\n### Server\n\nRequest smuggling when ember-server is an origin behind an intermediary that\nhonours `Transfer-Encoding` case-insensitively per RFC, forwards the header\nvalue verbatim, and reuses keep-alive connections to the backend:\n\n- Front-end security bypass: the smuggled request reaches paths the\n  intermediary's ACL/auth layer would have blocked, with attacker-chosen\n  method and headers.\n- Cross-user request hijack: a partial smuggled prefix left in Ember's\n  connection buffer is concatenated with the next victim's request on the\n  same pooled backend connection, exposing its headers (e.g. `Cookie`,\n  `Authorization`) to the attacker.\n- Cache poisoning: the smuggled response is associated with the next request\n  key in a caching proxy.\n\n### Client\n\nember-client shares the same `HeaderP.parse` on the response path, enabling\nresponse smuggling when http4s is used as a gateway. This is less severe: it\nrequires a malicious or compromised upstream rather than an anonymous remote\nclient.\n\n## Preconditions\n\n- Unauthenticated remote attacker (server)\n- ember-server as origin behind a keep-alive intermediary\n- Intermediary treats `Transfer-Encoding` case-insensitively (per RFC) and\n  forwards the header value without lowercasing it\n- Malicious or compromised upstream (client)\n\n## Workarounds\n\n- Intermediary fully buffers and re-encodes request bodies (e.g. nginx with\n  default `proxy_request_buffering on`)\n- Intermediary normalises the `Transfer-Encoding` value (lowercases the\n  token) before forwarding\n- Disable backend keep-alive between the intermediary and Ember","status":"published","published":"2026-09-15T19:54:25Z","modified":"2026-09-15T19:54:26Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T14:41:17.136201Z"}],"nvd":[{"id":"CVE-2026-69205","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T20:17:39.653Z","modified":"2026-09-16T20:38:04.943Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T14:12:47.974509Z"}],"osv":[{"id":"CVE-2026-69205","title":"Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:15:21.235Z","modified":"2026-10-28T02:30:22.045746495Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T15:45:15.164658Z"},{"id":"GHSA-9998-894r-fwvr","title":"Http4s Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)","description":"## Summary\n\nEmber's HTTP/1.1 header parser matches the `Transfer-Encoding` header value\nwith a case-sensitive substring test (`hValue.contains(\"chunked\")`). RFC\n9112 §7 requires transfer-coding names to be compared case-insensitively. A\nrequest carrying `Transfer-Encoding: Chunked` (capital C) is therefore not\nrecognised as chunked, and Ember falls back to framing by `Content-Length`\n(or zero if absent) while a compliant intermediary frames the same bytes by\nchunked encoding. The two parsers then disagree on where the request body\nends, enabling HTTP request smuggling (TE.CL / TE.0).\n\nThe same line of code admits two further variants:\n\n- The substring test misfires on `Transfer-Encoding: notchunked` (an inverse\n  desync — Ember treats it as chunked while a compliant intermediary\n  rejects the unknown coding).\n- Header field bytes are decoded with the platform-default charset. Under\n  UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which\n  `String.equalsIgnoreCase` Unicode-case-folds to `k`, so\n  `Transfer-Encoding: chun\u003cU+212A\u003eed` matches `chunked` once the comparison\n  is made case-insensitive without also pinning the decode to ISO-8859-1.\n\n## Impact\n\n### Server\n\nRequest smuggling when ember-server is an origin behind an intermediary that\nhonours `Transfer-Encoding` case-insensitively per RFC, forwards the header\nvalue verbatim, and reuses keep-alive connections to the backend:\n\n- Front-end security bypass: the smuggled request reaches paths the\n  intermediary's ACL/auth layer would have blocked, with attacker-chosen\n  method and headers.\n- Cross-user request hijack: a partial smuggled prefix left in Ember's\n  connection buffer is concatenated with the next victim's request on the\n  same pooled backend connection, exposing its headers (e.g. `Cookie`,\n  `Authorization`) to the attacker.\n- Cache poisoning: the smuggled response is associated with the next request\n  key in a caching proxy.\n\n### Client\n\nember-client shares the same `HeaderP.parse` on the response path, enabling\nresponse smuggling when http4s is used as a gateway. This is less severe: it\nrequires a malicious or compromised upstream rather than an anonymous remote\nclient.\n\n## Preconditions\n\n- Unauthenticated remote attacker (server)\n- ember-server as origin behind a keep-alive intermediary\n- Intermediary treats `Transfer-Encoding` case-insensitively (per RFC) and\n  forwards the header value without lowercasing it\n- Malicious or compromised upstream (client)\n\n## Workarounds\n\n- Intermediary fully buffers and re-encodes request bodies (e.g. nginx with\n  default `proxy_request_buffering on`)\n- Intermediary normalises the `Transfer-Encoding` value (lowercases the\n  token) before forwarding\n- Disable backend keep-alive between the intermediary and Ember","status":"published","published":"2026-09-15T19:54:25Z","modified":"2026-09-15T20:00:40.521015729Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T15:46:43.524801Z"}]}}