Use-after-free in OpenVPN Server - CVE-2026-12996
Published: July 2, 2026 / Updated: July 28, 2026
Vulnerability identifier: #VU139870
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-12996
CWE-ID: CWE-416
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 use-after-free in ack_write_buf() when processing a well-timed sequence of control channel and authentication packets. A remote attacker can send a specially crafted packet sequence to cause a denial of service.
How to mitigate CVE-2026-12996
Install security update from vendor's website.