CVE-2026-69204
Http4s Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggling)
Impact
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/1.1 does not reject messages containing both Transfer-Encoding and Content-Length, so an intermediary and Ember can select different body framing rules. When ember-server is behind a keep-alive intermediary that forwards both headers and frames by Content-Length, an unauthenticated attacker can smuggle a second request, bypass intermediary access controls, poison caches, or cause a victim request to be joined to an attacker-controlled prefix. The shared response parser can also desynchronize an ember-client connection when a malicious or compromised upstream sends both headers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| maven | org.http4s:http4s-ember-core_2.12 | <= 0.23.34 | 0.23.35 |
| maven | org.http4s:http4s-ember-core_2.13 | <= 0.23.34 | 0.23.35 |
| maven | org.http4s:http4s-ember-core_3 | <= 0.23.34 | 0.23.35 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-8h4c-x2wg-6xp8
- https://github.com/http4s/http4s/security/advisories/GHSA-8h4c-x2wg-6xp8
- https://github.com/http4s/http4s/commit/9feaf8677951a52af906ae9664ff6f0543d9d810
- https://github.com/http4s/http4s/releases/tag/v0.23.35
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47