CVE-2026-11771 - NTLM proxy auth stack off-by-one write

OpenVPN 2.x 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.

CVE Record: CVE-2026-11771

Github:

• OpenVPN/openvpn-private-issues#119

Release notes:

• openvpn-2.7.5
• openvpn-2.6.21

Reported-By: Tristan Madani (@TristanInSec)