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.

The remote Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8650-1 advisory.

    Chanho Kim and Jihyeok Han discovered that Cap'n Proto incorrectly handled negative Content-Length values     or excessively large chunk sizes when processing HTTP messages. An attacker could possibly use these     issues to cause HTTP messages to be interpreted inconsistently, resulting in HTTP request or response     smuggling. (CVE-2026-32239, CVE-2026-32240)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:21062-1 advisory.

    Update to version 1.4.0.

    Security issues fixed:

    - CVE-2026-32239: negative `Content-Length` conversion treated as impossibly large length by KJ-HTTP can     lead to HTTP       smuggling (bsc#1259638).
    - CVE-2026-32240: integer overflow when KJ-HTTP `Transfer-Encoding` chunk size is parsed to a value of     2^64 or larger       can lead to HTTP smuggling (bsc#1259639).

    Other updates and bugfixes:

    - Have `stdcoro` use `::std` namespace.
    - Disable stack check when HWASan is used.
    - Fix benign buffer overrun in async `readMessage()`.
    - Shared library naming changes from `libsomething-%{version}.so` to `libsomething.so.%{version}`.

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-32240)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
365438	Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : Cap'n Proto vulnerabilities (USN-8650-1)	Nessus	Ubuntu Local Security Checks	Local	medium
324073	openSUSE 16 Security Update : capnproto (openSUSE-SU-2026:21062-1)	Nessus	SuSE Local Security Checks	Local	medium
302170	Linux Distros Unpatched Vulnerability : CVE-2026-32240	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-32240

medium

Tenable Plugins

medium

medium

medium