Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, a negative Content-Length value was converted to unsigned, treating it as an impossibly large length instead. In theory, this bug could enable HTTP request/response smuggling. This vulnerability is fixed in 1.4.0.
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-qjx3-pp3m-9jpm