Capn Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, when using Transfer-Encoding: chunked, if a chunks 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.
Weakness
Truncation errors occur when a primitive is cast to a primitive of a smaller size and data is lost in the conversion.
Potential Mitigations
References
- https://capnproto.org/capnproto-c++-1.4.0.tar.gz
- https://capnproto.org/capnproto-c++-win32-1.4.0.zip
- https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36
- https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0
- https://github.com/capnproto/capnproto/security/advisories/GHSA-vpcq-mx5v-32wm