CVE-2026-32240
Cap'n Proto: Integer overflow in KJ-HTTP chunk size
- State
- Published
- Severity
- 6.3 Medium
- Published
- Mar 12, 2026
- Updated
- Mar 13, 2026
- Reserved
- Mar 11, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.3 Medium | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
capnprotocapnproto |
|
References
- https://github.com/capnproto/capnproto/security/advisories/GHSA-vpcq-mx5v-32wm
- https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36
- https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0
- https://capnproto.org/capnproto-c++-1.4.0.tar.gz
- https://capnproto.org/capnproto-c++-win32-1.4.0.zip
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