CVE-2026-11771

EUVD-2026-51237
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
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
OpenVPNCNA
7 HIGH
NETWORK
HIGH
NONE
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
openvpnopenvpn
2.1.0 ≤
𝑥
≤ 2.6.20
CNA
openvpnopenvpn
𝑥
≤ 2.7.4
CNA
Debian logo
Debian Releases
Debian Product
Codename
openvpn
bookworm
2.6.14-0+deb12u2
fixed
bookworm (security)
2.6.14-0+deb12u2
fixed
bullseye
vulnerable
bullseye (security)
vulnerable
forky
2.7.5-1
fixed
sid
2.7.5-1
fixed
trixie
2.6.14-1+deb13u3
fixed
trixie (security)
2.6.14-1+deb13u3
fixed
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
openvpn
Amazon Linux 2023
0:2.6.12-1.amzn2023.0.5
fixed
openvpn-debuginfo
Amazon Linux 2023
0:2.6.12-1.amzn2023.0.5
fixed
openvpn-debugsource
Amazon Linux 2023
0:2.6.12-1.amzn2023.0.5
fixed
openvpn-devel
Amazon Linux 2023
0:2.6.12-1.amzn2023.0.5
fixed
Common Weakness Enumeration
Vulnerability Media Exposure
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