CVE-2026-41070

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.

CVSS Details

CVSS Score

10.0

Severity

CRITICAL

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Configurations (Affected Products)

No configuration data available.

openvpn-auth-oauth2 1.26.3

openvpn-auth-oauth2 1.27.0

openvpn-auth-oauth2 1.27.1

openvpn-auth-oauth2 1.27.2

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# PoC Concept: Connect using standard OpenVPN client without WebAuth/SSO support
# The server running vulnerable version in experimental plugin mode will allow access.
openvpn --config <client_config_file>
# If vulnerable, connection is established without passing OIDC auth.

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-41070
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-41070
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-41070/
[4] VulDB https://vuldb.com/cve/CVE-2026-41070
[5] https://github.com/jkroepke/openvpn-auth-oauth2/commit/36f69a6c67c1054da7cbfa04ced3f0555127c8f2
[6] https://github.com/jkroepke/openvpn-auth-oauth2/security/advisories/GHSA-246w-jgmq-88fg

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-41070", "sourceIdentifier": "[email protected]", "published": "2026-05-08T16:16:11.030", "lastModified": "2026-05-08T16:16:11.030", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N", "baseScore": 10.0, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.8}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-287"}]}], "references": [{"url": "https://github.com/jkroepke/openvpn-auth-oauth2/commit/36f69a6c67c1054da7cbfa04ced3f0555127c8f2", "source": "[email protected]"}, {"url": "https://github.com/jkroepke/openvpn-auth-oauth2/security/advisories/GHSA-246w-jgmq-88fg", "source": "[email protected]"}]}}