NetSight
medium5.4

CVE-2026-69216

Http4s: Ember chunk parser lenience (TE.TE request smuggling)

Impact

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s chunk decoder trims the chunk-size token and accepts leading plus or minus signs instead of requiring one or more hexadecimal digits followed by the required CRLF. When an intermediary forwards chunked data without re-encoding and interprets malformed chunk boundaries differently, an unauthenticated attacker can create TE.TE request smuggling that bypasses intermediary controls, poisons caches, or hijacks the request queue. The same response-path leniency can enable response smuggling against an ember-client used as a gateway when the upstream is malicious or compromised. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Affected packages

EcosystemPackageAffectedFixed in
mavenorg.http4s:http4s-ember-core_2.12<= 0.23.340.23.35
mavenorg.http4s:http4s-ember-core_2.13<= 0.23.340.23.35
mavenorg.http4s:http4s-ember-core_3<= 0.23.340.23.35

Weakness classification

References