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Description

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.

PUBLISHED Reserved 2026-03-11 | Published 2026-03-12 | Updated 2026-03-13 | Assigner GitHub_M




MEDIUM: 6.3CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CWE-190: Integer Overflow or Wraparound

Product status

< 1.4.0
affected

References

github.com/...nproto/security/advisories/GHSA-qjx3-pp3m-9jpm

github.com/...ommit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36

github.com/...ommit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0

capnproto.org/capnproto-c++-1.4.0.tar.gz

capnproto.org/capnproto-c++-win32-1.4.0.zip

cve.org (CVE-2026-32239)

nvd.nist.gov (CVE-2026-32239)

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