CVE-2026-32240

CVE-2026-32240

Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, when using Transfer-Encoding: chunked, if a chunk's size parsed to a value of 2^64 or larger, it would be truncated to a 64-bit integer. In theory, this bug could enable HTTP request/response smuggling. This vulnerability is fixed in 1.4.0.

CVE-2026-32240

A flaw was found in the KJ-HTTP component of Cap’n Proto when processing HTTP messages that use Transfer-Encoding: chunked. If a chunk size is parsed as a value equal to or greater than 2^64, the value may be truncated when converted to a 64-bit integer. An attacker could exploit this behavior by sending specially crafted HTTP messages containing excessively large chunk sizes. This may cause incorrect interpretation of HTTP message boundaries and could theoretically enable HTTP request or response smuggling in applications that rely on the affected HTTP implementation.

CVE-2026-32240

Cap'n Proto is a data interchange format and capability-based RPC syst ...