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Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : libevent vulnerabilities (USN-8840-1)

high Nessus Plugin ID 351471

Synopsis

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

Description

The remote Ubuntu 14.04 LTS / 16.04 LTS / 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-8840-1 advisory.

 Micha Majchrowicz and Marcin Wyczechowski discovered that libevent incorrectly handled certain DNS responses. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-63387)

 It was discovered that libevent incorrectly handled certain connections. A local attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-63388)

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-8840-1

Plugin Details

Severity: High

ID: 351471

File Name: ubuntu_USN-8840-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 9/30/2026

Updated: 9/30/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.35

CVSS v2

Risk Factor: High

Base Score: 9

Temporal Score: 6.7

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

CVSS Score Source: CVE-2026-63387

CVSS v3

Risk Factor: High

Base Score: 8.4

Temporal Score: 7.3

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

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

CVSS Score Source: CVE-2026-63388

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:14.04:-:lts, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, 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:libevent-2.0-5, p-cpe:/a:canonical:ubuntu_linux:libevent-2.1-6, p-cpe:/a:canonical:ubuntu_linux:libevent-2.1-7, p-cpe:/a:canonical:ubuntu_linux:libevent-2.1-7t64, p-cpe:/a:canonical:ubuntu_linux:libevent-core-2.0-5, p-cpe:/a:canonical:ubuntu_linux:libevent-core-2.1-6, p-cpe:/a:canonical:ubuntu_linux:libevent-core-2.1-7, p-cpe:/a:canonical:ubuntu_linux:libevent-core-2.1-7t64, p-cpe:/a:canonical:ubuntu_linux:libevent-extra-2.0-5, p-cpe:/a:canonical:ubuntu_linux:libevent-extra-2.1-6, p-cpe:/a:canonical:ubuntu_linux:libevent-extra-2.1-7, p-cpe:/a:canonical:ubuntu_linux:libevent-extra-2.1-7t64, p-cpe:/a:canonical:ubuntu_linux:libevent-openssl-2.0-5, p-cpe:/a:canonical:ubuntu_linux:libevent-openssl-2.1-6, p-cpe:/a:canonical:ubuntu_linux:libevent-openssl-2.1-7, p-cpe:/a:canonical:ubuntu_linux:libevent-openssl-2.1-7t64, p-cpe:/a:canonical:ubuntu_linux:libevent-pthreads-2.0-5, p-cpe:/a:canonical:ubuntu_linux:libevent-pthreads-2.1-6, p-cpe:/a:canonical:ubuntu_linux:libevent-pthreads-2.1-7, p-cpe:/a:canonical:ubuntu_linux:libevent-pthreads-2.1-7t64

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

Exploit Ease: No known exploits are available

Patch Publication Date: 9/28/2026

Vulnerability Publication Date: 8/20/2026

Reference Information

CVE: CVE-2026-63387, CVE-2026-63388

USN: 8840-1