Input validation error in OpenVPN Server - CVE-2026-13122

Vulnerability identifier: #VU139872

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-13122

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper input validation in auth-token handling when processing a suitably malformed auth-token. A remote attacker can send a specially crafted auth-token to cause a denial of service.

Only servers with --auth-gen-token external-auth enabled are vulnerable.

OpenVPN Server
Debian Linux
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
Basesystem Module
openSUSE Leap
Ubuntu
openEuler
openvpn (Ubuntu package)
openvpn
openvpn-help
openvpn-devel
openvpn-debugsource
openvpn-debuginfo
openvpn-down-root-plugin-debuginfo
openvpn-down-root-plugin
openvpn-auth-pam-plugin
openvpn-auth-pam-plugin-debuginfo
openvpn-dco-debugsource
openvpn-dco-devel
openvpn-dco
openvpn-dco-debuginfo
openvpn (Debian package)

Install security update from vendor's website.

OpenVPN Server - addressed in versions 2.6.21, 2.7.5
openvpn (Ubuntu package) - addressed in versions 2.5.11-0ubuntu0.22.04.4, 2.6.19-0ubuntu0.24.04.3, 2.7.0-1ubuntu1.2
openvpn - update to 2.6.9-8
openvpn-help - update to 2.6.9-8
openvpn-devel - update to 2.6.9-8
openvpn-debugsource - update to 2.6.9-8
openvpn-debuginfo - update to 2.6.9-8
openvpn-down-root-plugin-debuginfo - update to 2.6.10-150600.3.23.1
openvpn-down-root-plugin - update to 2.6.10-150600.3.23.1
openvpn - update to 2.6.10-150600.3.23.1
openvpn-auth-pam-plugin - update to 2.6.10-150600.3.23.1
openvpn-devel - update to 2.6.10-150600.3.23.1
openvpn-auth-pam-plugin-debuginfo - update to 2.6.10-150600.3.23.1
openvpn-debuginfo - update to 2.6.10-150600.3.23.1
openvpn-dco-debugsource - update to 2.6.10-150600.3.23.1
openvpn-dco-devel - update to 2.6.10-150600.3.23.1
openvpn-dco - update to 2.6.10-150600.3.23.1
openvpn-debugsource - update to 2.6.10-150600.3.23.1
openvpn-dco-debuginfo - update to 2.6.10-150600.3.23.1
openvpn (Debian package) - update to 2.6.14-1+deb13u3

• https://github.com/OpenVPN/openvpn/releases/tag/v2.6.21
• https://github.com/OpenVPN/openvpn/commit/4dee614e4e799d6d4a20bffabd902291c86406f2

• Multiple vulnerabilities in OpenVPN Server
• Debian update for openvpn
• openEuler 24.03 LTS SP1 update for openvpn
• openEuler 24.03 LTS SP3 update for openvpn
• openEuler 24.03 LTS SP4 update for openvpn
• Ubuntu update for openvpn
• SUSE update for openvpn