Race condition in OpenVPN Server - CVE-2026-40215
Published: April 24, 2026
Vulnerability identifier: #VU127528
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-40215
CWE-ID: CWE-362
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 disclose packet data from a previous handshake.
The vulnerability exists due to a race condition in the TLS handshake handling when processing reconnecting sessions. A remote attacker can trigger repeated handshake activity to disclose packet data from a previous handshake.
This occurs only under specific circumstances involving replacement of an old TLS session by a new session while stale session state still attempts to send a packet.
How to mitigate CVE-2026-40215
Install security update from vendor's website.