CVE-2026-32240

EUVD-2026-11688
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
6.5 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 10%
Affected Products (NVD)
VendorProductVersion
capnprotocapnproto
𝑥
< 1.4.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
capnproto
bookworm
postponed
bullseye
postponed
forky
1.4.0-3
fixed
sid
1.4.0-3
fixed
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
capnproto
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
questing
ignored
resolute
needs-triage
trusty
needs-triage
xenial
needs-triage
Common Weakness Enumeration
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-vpcq-mx5v-32wm