Reachable assertion in OpenVPN Server - CVE-2025-2704

Vulnerability identifier: #VU106925

CSH Severity: Medium

CVSS v4 BT: 4.9 [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/E:U/U:Green]

CVE-ID: CVE-2025-2704

CWE-ID: CWE-617

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion in server mode using TLS-crypt-v2. A remote attacker can perform a denial of service attack against the VPN server by replaying network packets in the early handshake phase.

Successful exploitation of the vulnerability requires a valid tls-crypt-v2 client key or network observation of a handshake with a valid tls-crypt-v2 client key.

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

Install updates from vendor's website.

OpenVPN Server - update to 2.6.14
openvpn-debuginfo - update to 2.6.8-150600.3.17.1
openvpn-dco-devel - update to 2.6.8-150600.3.17.1
openvpn-dco - update to 2.6.8-150600.3.17.1
openvpn-auth-pam-plugin-debuginfo - update to 2.6.8-150600.3.17.1
openvpn-dco-debuginfo - update to 2.6.8-150600.3.17.1
openvpn-dco-debugsource - update to 2.6.8-150600.3.17.1
openvpn-down-root-plugin - update to 2.6.8-150600.3.17.1
openvpn - update to 2.6.8-150600.3.17.1
openvpn-debugsource - update to 2.6.8-150600.3.17.1
openvpn-auth-pam-plugin - update to 2.6.8-150600.3.17.1
openvpn-devel - update to 2.6.8-150600.3.17.1
openvpn-down-root-plugin-debuginfo - update to 2.6.8-150600.3.17.1
openvpn-help - update to 2.6.9-4
openvpn - update to 2.6.9-4
openvpn-debuginfo - update to 2.6.9-4
openvpn-debugsource - update to 2.6.9-4
openvpn-devel - update to 2.6.9-4
openvpn (Ubuntu package) - addressed in versions 2.6.12-0ubuntu0.24.04.3, 2.6.12-1ubuntu1.2
openvpn - addressed in versions 2.6.14-1.fc40, 2.6.14-1.fc41, 2.6.14-1.fc42

• http://www.openwall.com/lists/oss-security/2025/04/02/5
• https://community.openvpn.net/openvpn/wiki/CVE-2025-2704

• Remote denial of service in OpenVPN server
• Fedora 42 update for openvpn
• Fedora 41 update for openvpn
• Fedora 40 update for openvpn
• Ubuntu update for openvpn
• openEuler 24.03 LTS update for openvpn
• openEuler 24.03 LTS SP1 update for openvpn
• SUSE update for openvpn
• SUSE update for openvpn