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

Code

The project this record applies to. Exploit listings stay in References.

• Repository · github.com

Timeline

Detection, updates, and resolution for this record.

1. Mar 12, 2026 · NIST NVD

   Detected

   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.

2. Jun 17, 2026 · NIST NVD

   Updated

   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.

Affected

• cpe capnproto/capnprotoversion unspecified

Sources

• NIST NVDVulnerability recordCVE-2026-32239

  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 vulnerabi

  nvd.nist.gov

References

• Product · capnproto.org
• Product · capnproto.org
• Patch · github.com
• Patch · github.com
• Vendor Advisory · github.com