Vulnerability · Published May 8, 2026 · Assigned by GitHub_M
CVE-2026-41070openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access
Critical 10.0
In plain English
A critical-severity improper authentication in openvpn-auth-oauth2 from jkroepke. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | openvpn-auth-oauth2 | 1.27.3-1 | DEBIAN-CVE-2026-41070 |
| Go | github.com/jkroepke/openvpn-auth-oauth2 | 1.27.3 | GHSA-246w-jgmq-88fg |
| Go | github.com/jkroepke/openvpn-auth-oauth2 | 1.27.3 | GO-2026-4963 |
| Ubuntu:26.10 | openvpn-auth-oauth2 | no fix listed | UBUNTU-CVE-2026-41070 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| jkroepke | openvpn-auth-oauth2 | >= 1.26.3, < 1.27.3 |
Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N