CVE-2026-11771: Openvpn

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

OpenVPN version 2.1.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows attackers via an off-by-one buffer write in the NTLM proxy authentication to potentially cause a crash via a crafted NTLM response from a malicious proxy server

Affected products

• Openvpn Openvpn: from 2.1.0, before 2.6.21 (fixed in 2.6.21); from 2.7, before 2.7.5 (fixed in 2.7.5)

Published 2026-07-30. Last modified 2026-08-05.