Remote denial of service in OpenVPN server



Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2025-2704
CWE-ID CWE-617
Exploitation vector Network
Public exploit N/A
Vulnerable software
 OpenVPN Server
Server applications / Remote access servers, VPN

Vendor OpenVPN

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Reachable assertion

EUVDB-ID: #VU106925

Risk: Medium

CVSSv4.0: 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 - Reachable Assertion

Exploit availability: No

Description

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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

OpenVPN Server: 2.6.1 - 2.6.13

CPE2.3 External links

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


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.



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