Out-of-bounds read in OpenVPN Server - CVE-2026-78221
Published: September 5, 2026
Vulnerability identifier: #VU147009
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-78221
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to an out-of-bounds read in openvpnserv when processing NRPT domains with UTF-8-encoded IDN domains. A remote attacker can supply UTF-8-encoded IDN domains to disclose sensitive information.
Affected software
OpenVPN Server
How to mitigate CVE-2026-78221
Install security update from vendor's website.
OpenVPN Server - update to 2.7.7