Auth bypass in Jkroepke Openvpn-Auth-Oauth2

CVE-2026-41070

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.

Vulnerability class: Broken Authentication

Published · last modified .

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.006 (45.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-41070: held from 0.004 to 0.006.

EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-41070?
CVE-2026-41070 is a critical-severity vulnerability in Jkroepke Openvpn-Auth-Oauth2, classified under Improper Authentication. CVSS score: 10.0/10. Published 2026-05-08.
How severe is CVE-2026-41070?
Critical severity. CVSS v3 base score is 10.0 out of 10.