CVE-2026-41070CWE-287

openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access

Critical · published May 8, 2026

CVSS v3.1
10.0
EPSS
1%
Percentile
46.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
10.0 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00578 · 46.8th percentile
Weakness
CWE-287 · Improper Authentication
Published
2026-05-08T15:14Z
EPSS history
Timeline
  • 08 MAY 15:14Z
    openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access
    cvelistv5