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

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4666-1 openvpn security update
Debian DSA Debian DSA DSA-6376-1 openvpn security update
Ubuntu USN Ubuntu USN USN-8540-1 OpenVPN vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 30 Jul 2026 18:45:00 +0000

Type Values Removed Values Added
First Time appeared Openvpn
Openvpn openvpn
Vendors & Products Openvpn
Openvpn openvpn

Thu, 30 Jul 2026 17:00:00 +0000

Type Values Removed Values Added
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
Weaknesses CWE-121
CWE-193
CWE-787
References
Metrics cvssV4_0

{'score': 7, '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: OpenVPN

Published:

Updated: 2026-07-30T18:04:42.335Z

Reserved: 2026-06-09T11:44:10.570Z

Link: CVE-2026-11771

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-30T18:30:04Z

Weaknesses