CVE-2026-41070 openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access
Attackers can bypass authentication and gain unauthenticated VPN access when using the experimental plugin mode in openvpn-auth-oauth2.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41070?
CVE-2026-41070 is a critical authentication bypass vulnerability in jkroepke openvpn-auth-oauth2, published on 8 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
openvpn-auth-oauth2 is a plugin/management interface client for OpenVPN server to handle an OIDC based single sign-on (SSO) auth flows. From version 1.26.3 to before version 1.27.3, when openvpn-auth-oauth2 is deployed in the experimental plugin mode (shared library loaded by OpenVPN via the plugin directive), clients that do not support WebAuth/SSO (e.g., the openvpn CLI on Linux) are incorrectly admitted to the VPN despite being denied by the authentication logic. The default management-interface mode is not affected because it does not use the OpenVPN plugin return-code mechanism. This issue has been patched in version 1.27.3.
Weakness: CWE-287
Which versions are affected by CVE-2026-41070?
3 open source packages ship an affected version, including github.com/jkroepke/openvpn-auth-oauth2.
| Package | Affected | Fixed in |
|---|---|---|
github.com/jkroepke/openvpn-auth-oauth2 Go | From 1.26.3 | 1.27.3 |
github.com/jkroepke/openvpn-auth-oauth2 Go | From 1.26.3 | 1.27.3 |
github.com/jkroepke/openvpn-auth-oauth2 Go | From 1.26.3 | 1.27.3 |
How do I fix CVE-2026-41070?
Upgrade github.com/jkroepke/openvpn-auth-oauth2 to 1.27.3 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-41070 being exploited?
There is no known exploitation of CVE-2026-41070 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-41070, GHSA-246w-jgmq-88fg, GO-2026-4963, UBUNTU-CVE-2026-41070.