openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| jkroepke | openvpn-auth-oauth2 | 1.26.3 to before 1.27.3 | 1.27.3 | Patch available | CNA |
| — | github.com/jkroepke/openvpn-auth-oauth2 (Go) | 1.26.3 to before 1.27.3 | 1.27.3 | Patch available | GHSA-246w-jgmq-88fg |
- openvpn-auth-oauth2 Vendorjkroepke Affected 1.26.3 to before 1.27.3 Fixed in 1.27.3 Patch available CNA
- github.com/jkroepke/openvpn-auth-oauth2 (Go) Vendor— Affected 1.26.3 to before 1.27.3 Fixed in 1.27.3 Patch available GHSA-246w-jgmq-88fg
Remediation
- Fix · CNA openvpn-auth-oauth2 (jkroepke) Fixed in 1.27.3
- Fix · GHSA-246w-jgmq-88fg github.com/jkroepke/openvpn-auth-oauth2 (Go) Fixed in 1.27.3 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-41070
- 2026-10-03 Alias added: GHSA-246w-jgmq-88fg
References
Other 7
- https://github.com/jkroepke/openvpn-auth-oauth2/security/advisories/GHSA-246w-jgmq-88fg
- https://github.com/jkroepke/openvpn-auth-oauth2/commit/36f69a6c67c1054da7cbfa04ced3f0555127c8f2
- https://github.com/jkroepke/openvpn-auth-oauth2/pull/829
- https://github.com/OpenVPN/openvpn/blob/master/include/openvpn-plugin.h.in
- https://github.com/OpenVPN/openvpn3/blob/master/doc/webauth.md
- https://github.com/jkroepke/openvpn-auth-oauth2
- https://github.com/jkroepke/openvpn-auth-oauth2/releases/tag/v1.27.3
Sources
- CVE-2026-41070 · CVE Program
- CVE-2026-41070 · NVD
- FIRST EPSS
- GHSA-246w-jgmq-88fg · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences