Out-of-bounds write in OpenVPN Server - CVE-2026-11771
Published: July 2, 2026 / Updated: July 28, 2026
Vulnerability identifier: #VU139874
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-11771
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: OpenVPN
Affected software:
OpenVPN Server
OpenVPN Server
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to out-of-bounds write in NTLMv2 proxy responses when parsing response data. A remote attacker can send specially crafted response data to cause a denial of service.
The advisory describes the overrun as limited to one byte.
How to mitigate CVE-2026-11771
Install security update from vendor's website.