CVE-2026-32240 MEDIUM

CVE-2026-32240: Cap'n Proto: Integer overflow in KJ-HTTP chunk size

Vendor Capnproto
Product capnproto
Weakness CWE-197
Published March 12, 2026
Last update March 13, 2026
View on NVD All CVEs

CVSS base score

6.3/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 12, 2026 CVE published
March 13, 2026 Record updated