CVE-2026-11771

State: Published
Severity: 7.0 High
Published: Jul 30, 2026
Updated: Jul 30, 2026
Reserved: Jun 9, 2026

Description

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

Scores

CVSS	Score	Vector	Source
4.0	7.0 High	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	OpenVPN

Weaknesses

CWE-193 Off-by-one error
CWE-121 Stack-based buffer overflow
CWE-787 Out-of-bounds write

Affected Products

Product	Versions
OpenVPNOpenVPN	2.1.0 through 2.6.20Affected 2.7_alpha1 through 2.7.4Affected

References

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

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