{"id":"CVE-2026-69217","aliases":["EUVD-2026-79193","GHSA-p83c-4wj9-p6w9"],"status":"published","title":"Http4s: Ember Server accepts duplicate Content-Length headers","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/1.1 parser accepts differing duplicate Content-Length headers and uses the last value instead of rejecting the message. When an Ember server is behind a keep-alive intermediary that selects a different occurrence, an unauthenticated attacker can create CL.CL request smuggling that bypasses front-end controls, captures a later user’s headers, or poisons a cache. The shared client parser can also misframe responses from a malicious or compromised upstream when the client acts as a proxy for multiple downstream consumers. 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":0.00499,"percentile":0.43026,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-444"],"published":"2026-09-15T19:20:02Z","modified":"2026-10-28T02:30:41Z","products":[{"vendor":"http4s","product":"http4s"}],"references":[{"url":"https://github.com/http4s/http4s/security/advisories/GHSA-p83c-4wj9-p6w9","tags":["x_refsource_CONFIRM","advisory"]},{"url":"https://github.com/http4s/http4s/commit/24e8d34e3ea89f8f23e0053ec9944f6467e8086d","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/http4s/http4s/releases/tag/v0.23.35","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/http4s/http4s/releases/tag/v1.0.0-M47","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69217.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-69217","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-69217","title":"Http4s: Ember Server accepts duplicate Content-Length headers","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/1.1 parser accepts differing duplicate Content-Length headers and uses the last value instead of rejecting the message. When an Ember server is behind a keep-alive intermediary that selects a different occurrence, an unauthenticated attacker can create CL.CL request smuggling that bypasses front-end controls, captures a later user’s headers, or poisons a cache. The shared client parser can also misframe responses from a malicious or compromised upstream when the client acts as a proxy for multiple downstream consumers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:20:02.902Z","modified":"2026-09-16T13:52:40.263Z","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":"2026-11-02T13:50:27.582139Z"}],"euvd":[{"id":"EUVD-2026-79193","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/1.1 parser accepts differing duplicate Content-Length headers and uses the last value instead of rejecting the message. When an Ember server is behind a keep-alive intermediary that selects a different occurrence, an unauthenticated attacker can create CL.CL request smuggling that bypasses front-end controls, captures a later user’s headers, or poisons a cache. The shared client parser can also misframe responses from a malicious or compromised upstream when the client acts as a proxy for multiple downstream consumers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:20:02Z","modified":"2026-09-16T13:52:40Z","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":"2026-11-02T17:28:16.201278Z"}],"nvd":[{"id":"CVE-2026-69217","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/1.1 parser accepts differing duplicate Content-Length headers and uses the last value instead of rejecting the message. When an Ember server is behind a keep-alive intermediary that selects a different occurrence, an unauthenticated attacker can create CL.CL request smuggling that bypasses front-end controls, captures a later user’s headers, or poisons a cache. The shared client parser can also misframe responses from a malicious or compromised upstream when the client acts as a proxy for multiple downstream consumers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T20:17:41.12Z","modified":"2026-09-16T20:39:16.61Z","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-2026-69217","title":"Http4s: Ember Server accepts duplicate Content-Length headers","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/1.1 parser accepts differing duplicate Content-Length headers and uses the last value instead of rejecting the message. When an Ember server is behind a keep-alive intermediary that selects a different occurrence, an unauthenticated attacker can create CL.CL request smuggling that bypasses front-end controls, captures a later user’s headers, or poisons a cache. The shared client parser can also misframe responses from a malicious or compromised upstream when the client acts as a proxy for multiple downstream consumers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:20:02.902Z","modified":"2026-10-28T02:30:41.561367179Z","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"}]}}