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Vulnerability record · CVE-2026-11771 · published 30 July 2026

CVE-2026-11771: Openvpn stack-based buffer overflow vulnerability

Openvpn · Openvpn

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

7.0 CVSS 4.0 High EPSS 0.68% · top 49.4% CWE-121 · Stack-based buffer overflowCWE-193 · CWE-193
7.0CVSS 4.0 base score
0.68%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
5 Aug 2026Last modified by NVD

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

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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://community.openvpn.net/ReleaseHistory#openvpn-2621-released-1-july-2026 Release Notes
https://community.openvpn.net/ReleaseHistory#openvpn-275-released-1-july-2026 Release Notes
https://community.openvpn.net/Security%20Announcements/CVE-2026-11771 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-11771), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.