CVE-2026-11771

EUVD-2026-51237 · Published Jul 30, 2026

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

Technologies

Openvpn Openvpn

Weaknesses

CWE-193CWE-787CWE-121

CVSS scores

v4.07.0CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
v3.17.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

https://community.openvpn.net/ReleaseHistory#openvpn-2621-released-1-july-2026
https://community.openvpn.net/ReleaseHistory#openvpn-275-released-1-july-2026
https://community.openvpn.net/Security%20Announcements/CVE-2026-11771

Potentially impacted assets

See if this affects your attack surface