CVE-2026-69204: Http4s Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggling)
Ember’s HTTP/1.1 request parser does not reject a message that carries both a
Transfer-Encoding and a Content-Length header. RFC 9112 §6.1 requires a
server to treat such a message as a framing error and close the connection.
An intermediary that follows the RFC’s CL-strip-and-forward path (or that
prioritises Content-Length) will frame the body differently from Ember,
enabling HTTP request smuggling (CL.TE).
References
- github.com/advisories/GHSA-8h4c-x2wg-6xp8
- github.com/http4s/http4s/commit/9feaf8677951a52af906ae9664ff6f0543d9d810
- github.com/http4s/http4s/releases/tag/v0.23.35
- github.com/http4s/http4s/releases/tag/v1.0.0-M47
- github.com/http4s/http4s/security/advisories/GHSA-8h4c-x2wg-6xp8
- nvd.nist.gov/vuln/detail/CVE-2026-69204
Code Behaviors & Features
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