# CVE-2026-32240

## Summary

- **CVE ID:** CVE-2026-32240
- **Severity:** MEDIUM
- **CVSS Score:** 6.3 (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)
- **CWE:** CWE-197, CWE-444
- **Published:** Mar 12, 2026
- **Last Modified:** Mar 16, 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.

## Affected Products

- capnproto — capnproto (< 1.4.0)

## References

- [CNA](https://github.com/capnproto/capnproto/security/advisories/GHSA-vpcq-mx5v-32wm)
- [CNA](https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36)
- [CNA](https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0)
- [CNA](https://capnproto.org/capnproto-c++-1.4.0.tar.gz)
- [CNA](https://capnproto.org/capnproto-c++-win32-1.4.0.zip)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.21%
- **EPSS Percentile:** 10.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._