CVE-2026-69216: Http4s Ember Chunk Parser Lenience (TE.TE Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jrpm-956j-96jg",
  "modified" : "2026-09-15T20:01:00Z",
  "published" : "2026-09-15T20:01:00Z",
  "aliases" : [ "CVE-2026-69216" ],
  "summary" : "Http4s: Ember chunk parser lenience (TE.TE request smuggling)",
  "details" : "## Summary\n\nEmber's chunk decoder parses the size token leniently: it strips leading and trailing whitespace and accepts a leading `+` or `-` sign.  RFC9112 §7.1 defines `chunk-size = 1*HEXDIG`.  An intermediary that parses the chunk boundary differently (or rejects it) will disagree with Ember on request framing, enabling HTTP request smuggling (TE.TE).\n\n## Impact\n\n### Server\n\nRequest smuggling (TE.TE) when ember-server is an origin behind an intermediary that forwards the body verbatim but interprets the malformed chunk sizes differently\n\n- Front-end security bypass: the smuggled request reaches paths the intermediary might have blocked, with attacker-chosen method and headers.\n- Cache poisoning: the smuggled response is associated with the next request key in a caching proxy.\n- Request queue hijack:\n\n### Client\n\nember-client has the same leniencies on the response path, which enables response smuggling when http4s is used as a gateway.  This is less severe, as it requires a malicious or compromised upstream rather than an anonymous remote client.\n\n## Preconditions\n\n- Unauthenticated remote attacker (server)\n- ember-server as origin behind a keep-alive intermediary\n- Malicious or compromised upstream (client)\n- Intermediary or upstream forwards chunked bodies without re-encoding and disagrees with Ember on `+` prefix, `-` prefix, or leading and trailing octets rather than rejecting.\n\n## Workarounds\n\n- Intermediary strictly rejects malformed chunk sizes\n- Intermediary buffers and re-encodes request bodies\n\n## References\n\n- [RFC9112 §7.1: Chunked Transfer Coding](https://www.rfc-editor.org/rfc/rfc9112.html#name-chunked-transfer-coding)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_2.12"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.35"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.23.34"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_2.13"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.35"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.23.34"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.35"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.23.34"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_2.13"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0-M1"
      }, {
        "fixed" : "1.0.0-M47"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.0-M46"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0-M1"
      }, {
        "fixed" : "1.0.0-M47"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.0-M46"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/security/advisories/GHSA-jrpm-956j-96jg"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/commit/d78612a5abd5a2547487598d3342be05573e16f0"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/http4s/http4s"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/releases/tag/v0.23.35"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/releases/tag/v1.0.0-M47"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-444" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-15T20:01:00Z",
    "nvd_published_at" : null
  }
}