Race condition in OpenVPN Server - CVE-2026-40215

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Main Vulnerability Database Vulnerabilities #VU127528

Race condition in OpenVPN Server - CVE-2026-40215

Published: April 24, 2026


Vulnerability identifier: #VU127528
CSH Severity: Low
CVSS v4: 6.3 [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]
CVE-ID: CVE-2026-40215
CWE-ID: CWE-362
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

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.


Affected software

OpenVPN Server
Debian Linux
Fedora
openEuler
Ubuntu
openvpn
openvpn-debuginfo
openvpn-debugsource
openvpn-devel
openvpn-help
openvpn (Ubuntu package)
openvpn (Debian package)

How to mitigate CVE-2026-40215

Install security update from vendor's website.

OpenVPN Server - addressed in versions 2.6.20, 2.7.2
openvpn - addressed in versions 2.4.8-12, 2.5.5-7, 2.6.9-7
openvpn-debuginfo - addressed in versions 2.4.8-12, 2.5.5-7, 2.6.9-7
openvpn-debugsource - addressed in versions 2.4.8-12, 2.5.5-7, 2.6.9-7
openvpn-devel - addressed in versions 2.4.8-12, 2.5.5-7, 2.6.9-7
openvpn-help - addressed in versions 2.4.8-12, 2.5.5-7, 2.6.9-7
openvpn (Ubuntu package) - addressed in versions 2.5.11-0ubuntu0.22.04.3, 2.6.19-0ubuntu0.24.04.2, 2.6.19-0ubuntu0.25.10.2, 2.7.0-1ubuntu1.1
openvpn (Debian package) - addressed in versions 2.6.14-0+deb12u1, 2.6.14-1+deb13u2
openvpn - addressed in versions 2.6.20-1.fc42, 2.6.20-1.fc43, 2.7.2-1.el10_1, 2.7.2-1.el10_2, 2.7.2-1.el10_3, 2.7.2-1.fc44, 2.7.3-1.el10_1, 2.7.3-1.el10_2, 2.7.3-1.el10_3, 2.7.3-1.fc44

External References

Related Security Bulletins