CVE-2026-32240: Cap'n Proto: Integer overflow in KJ-HTTP chunk size
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/capnprototo a version that resolves this vulnerability.Fixed in 1.4.0-3 - Upgrade
Upgrade
Cap'n Prototo a version that resolves this vulnerability.Fixed in 1.4.0
Event History
Frequently Asked Questions
What is the severity of CVE-2026-32240?
The severity of CVE-2026-32240 is considered to be critical due to the potential for integer overflow vulnerabilities.
How do I fix CVE-2026-32240?
To fix CVE-2026-32240, upgrade Cap'n Proto to version 1.4.0 or later to mitigate the vulnerability.
What causes the CVE-2026-32240 vulnerability?
CVE-2026-32240 is caused by an integer overflow in KJ-HTTP when handling chunk sizes parsed as 2^64 or larger.
Which versions of Cap'n Proto are affected by CVE-2026-32240?
Cap'n Proto versions prior to 1.4.0 are affected by CVE-2026-32240.
Can CVE-2026-32240 lead to security breaches?
Yes, CVE-2026-32240 can potentially lead to security breaches if exploited, allowing attackers to manipulate data.