What is CVE-2026-11771?

CVE-2026-11771 is a high-severity vulnerability in Openvpn, classified under Stack-based Buffer Overflow. CVSS score: 7.5/10. Published 2026-07-30.

How severe is CVE-2026-11771?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Openvpn

CVE-2026-11771

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

Vulnerability class: Buffer Overflow

EPSS: 0.004 (30.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Openvpn — versions 2.1.0, 2.7_alpha1

Weakness classification (CWE)

References

security@openvpn.net (vendor-advisory, Vendor Advisory)
security@openvpn.net (release-notes, Release Notes)
security@openvpn.net (release-notes, Release Notes)

Frequently asked questions

What is CVE-2026-11771?: CVE-2026-11771 is a high-severity vulnerability in Openvpn, classified under Stack-based Buffer Overflow. CVSS score: 7.5/10. Published 2026-07-30.
How severe is CVE-2026-11771?: High severity. CVSS v3 base score is 7.5 out of 10.