Name: CVE-2026-11771: Off-by-one Error
Creator: Rapid7
Published: 2026-07-30T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-11771, CWE-787, CWE-121, CWE-193, CVSS 7.5, EPSS 0.00684

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

CVSS Details

CVSS 4.0 Base Score: 7 (HIGH)
CVSS 4.0 Vector: (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/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)
CVSS 3.1 Base Score: 7.5
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Alpine Linux	—	Upgrade openvpn	Jul 31, 2026	Jul 30, 2026
Debian	—	Upgrade openvpn	Jul 5, 2026	Jul 5, 2026
Freebsd	—	Upgrade openvpnUpgrade openvpn-devel	Jul 7, 2026	Jul 1, 2026
Ubuntu	—	Upgrade openvpn	Jul 15, 2026	Jul 14, 2026

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CVSS Details

Covered by Rapid7

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