CVE-2026-11771

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-30 · updated 2026-08-05
Weakness: CWE-121

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

Affected products

OpenVPN: from 2.1.0 before 2.6.21; from 2.7 before 2.7.5 — fixed in 2.6.21, 2.7.5

How to fix

Upgrade to a fixed version: OpenVPN 2.6.21, 2.7.5. Check the vendor advisory for mitigations.

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

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