---
title: "CVE-2026-41070: openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access"
url: https://erroneo.us/security/cve/CVE-2026-41070/
description: "CVE-2026-41070 (github.com/jkroepke/openvpn-auth-oauth2 (Go)): openvpn-auth-oauth2 is a plugin/management interface client for OpenVPN server to handle an…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-08
date_modified: 2026-05-13
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-41070"
kev: false
cvss: 10
epss: 0.00578
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-41070: openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.6% , percentile 47: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 47% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/jkroepke/openvpn-auth-oauth2 (Go) >= 1.26.3, < 1.27.3, fixed in 1.27.3 . Check your lockfile, including transitive dependencies.

## 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.

## Affected packages

- Go `github.com/jkroepke/openvpn-auth-oauth2` >= 1.26.3, < 1.27.3 → fixed: 1.27.3

## Affected products (CVE record)

- jkroepke openvpn-auth-oauth2: >= 1.26.3, < 1.27.3

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.58% probability of exploitation activity in the next 30 days; percentile 47.

## Sources

- [GitHub Advisory GHSA-246w-jgmq-88fg](https://github.com/advisories/GHSA-246w-jgmq-88fg)
- [CVE.org record CVE-2026-41070](https://www.cve.org/CVERecord?id=CVE-2026-41070)
- [NVD entry CVE-2026-41070](https://nvd.nist.gov/vuln/detail/CVE-2026-41070)
- [github.com](https://github.com/jkroepke/openvpn-auth-oauth2/security/advisories/GHSA-246w-jgmq-88fg)
- [github.com](https://github.com/jkroepke/openvpn-auth-oauth2/commit/36f69a6c67c1054da7cbfa04ced3f0555127c8f2)
- [github.com](https://github.com/jkroepke/openvpn-auth-oauth2/pull/829)
- [github.com](https://github.com/OpenVPN/openvpn/blob/master/include/openvpn-plugin.h.in)
- [github.com](https://github.com/OpenVPN/openvpn3/blob/master/doc/webauth.md)
- [github.com](https://github.com/jkroepke/openvpn-auth-oauth2/releases/tag/v1.27.3)

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Source page: https://erroneo.us/security/cve/CVE-2026-41070/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt