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Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : Cap'n Proto vulnerabilities (USN-8650-1)

medium Nessus Plugin ID 365438

Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

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.

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-8650-1

Plugin Details

Severity: Medium

ID: 365438

File Name: ubuntu_USN-8650-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 10/13/2026

Updated: 10/13/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 2.1

Percentile: 7.51

CVSS v2

Risk Factor: Medium

Base Score: 6.4

Temporal Score: 4.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N

CVSS Score Source: CVE-2026-32240

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS v4

Risk Factor: Medium

Base Score: 6.3

Threat Score: 1.7

Threat Vector: CVSS:4.0/E:U

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:capnproto, p-cpe:/a:canonical:ubuntu_linux:libcapnp-0.6.1, p-cpe:/a:canonical:ubuntu_linux:libcapnp-0.7.0, p-cpe:/a:canonical:ubuntu_linux:libcapnp-0.8.0, p-cpe:/a:canonical:ubuntu_linux:libcapnp-1.0.1, p-cpe:/a:canonical:ubuntu_linux:libcapnp-1.1.0

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 8/19/2026

Vulnerability Publication Date: 3/12/2026

Reference Information

CVE: CVE-2026-32239, CVE-2026-32240

USN: 8650-1