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Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenVPN vulnerabilities (USN-8540-1)

high Nessus Plugin ID 326999

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Synopsis

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

Description

The remote Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-8540-1 advisory.

 It was discovered that OpenVPN had a 1-byte buffer overrun when handling NTLMv2 proxy responses. An attacker could use this issue to cause a denial of service or possibly execute arbitrary code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-11771)

 It was discovered that OpenVPN incorrectly handled metadata when extracting tls-crypt-v2 client keys. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-12932)

 It was discovered that OpenVPN had a use-after-free in the ack_write_buf handling. An attacker could use this issue to cause OpenVPN to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-12996)

 It was discovered that OpenVPN had a use-after-free in the tls_wrap_reneg handling. An attacker could use this issue to cause OpenVPN to crash, resulting in a denial of service, or possibly execute arbitrary code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13117)

 It was discovered that OpenVPN incorrectly validated authentication tokens when external authentication was enabled. A remote attacker could possibly use this issue to cause OpenVPN to crash, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13122)

 It was discovered that OpenVPN had a memory leak when handling tls-crypt-v2 client keys. A remote attacker with a valid tls-crypt-v2 client key could possibly use this issue to cause OpenVPN to consume excessive resources, leading to a denial of service. (CVE-2026-13698)

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 openvpn package.

See Also

https://ubuntu.com/security/notices/USN-8540-1

Plugin Details

Severity: High

ID: 326999

File Name: ubuntu_USN-8540-1.nasl

Version: 1.3

Type: Local

Agent: unix

Published: 7/15/2026

Updated: 8/6/2026

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: 4.3

Percentile: 53.59

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 6.3

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

CVSS Score Source: CVE-2026-13117

CVSS v3

Risk Factor: High

Base Score: 8.1

Temporal Score: 7.1

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

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

CVSS v4

Risk Factor: High

Base Score: 7.1

Threat Score: 4.9

Threat Vector: CVSS:4.0/E:U

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

CVSS Score Source: CVE-2026-12932

Vulnerability Information

CPE: 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:openvpn

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

Exploit Ease: No known exploits are available

Patch Publication Date: 7/14/2026

Vulnerability Publication Date: 7/1/2026

Reference Information

CVE: CVE-2026-11771, CVE-2026-12932, CVE-2026-12996, CVE-2026-13117, CVE-2026-13122, CVE-2026-13698

IAVA: 2026-A-0662

USN: 8540-1