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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-8710-1)

critical Nessus Plugin ID 365422

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-8710-1 advisory.

 Alexis Challande discovered that libevent incorrectly handled certain empty output buffers. An attacker could possibly use this issue to trigger a use-after-free, resulting in a denial of service or arbitrary code execution. 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-2026-63381)

 Rajat Raghav discovered that libevent incorrectly handled certain HTTP requests. An attacker could possibly use this issue to desynchronize HTTP request boundaries, resulting in HTTP request smuggling.
 (CVE-2026-63382)

 Qiu Sihao discovered that libevent incorrectly handled certain malformed tagged RPC data. An attacker could possibly use this issue to trigger an out-of-bounds read, resulting in a denial of service.
 (CVE-2026-63383)

 Qiu Sihao discovered that libevent incorrectly handled certain large payload lengths in tagged RPC data.
 An attacker could possibly use this issue to consume excessive system resources, resulting in a denial of service. (CVE-2026-63384)

 Asaf Meizner discovered that libevent incorrectly handled certain HTTP URIs and header values. An attacker could possibly use this issue to cause HTTP messages to be interpreted inconsistently, resulting in security restrictions being bypassed. (CVE-2026-63385)

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-8710-1

Plugin Details

Severity: Critical

ID: 365422

File Name: ubuntu_USN-8710-1.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: Medium

Score: 4.5

Percentile: 57.72

CVSS v2

Risk Factor: High

Base Score: 7.3

Temporal Score: 5.4

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

CVSS Score Source: CVE-2026-63385

CVSS v3

Risk Factor: High

Base Score: 7.7

Temporal Score: 6.7

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

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

CVSS v4

Risk Factor: Critical

Base Score: 9.2

Threat Score: 7.1

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:L/SA:N

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/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 9/1/2026

Vulnerability Publication Date: 8/20/2026

Reference Information

CVE: CVE-2026-63381, CVE-2026-63382, CVE-2026-63383, CVE-2026-63384, CVE-2026-63385

USN: 8710-1