openvpn-auth-oauth2 — security advisory

{
  "id": "63255022ba35f5fe5fdeba61adff0b841f448fd94bf70881a9ff10fe6e438626",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-41070",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-41070",
    "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.",
    "evidence": "osv:UBUNTU-CVE-2026-41070",
    "products": [
      {
        "name": {
          "value": "openvpn-auth-oauth2",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.27.0-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.28.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.28.3-2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "openvpn-auth-oauth2",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.27.0-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.27.0-2ubuntu0.1~esm1",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "UBUNTU-CVE-2026-41070",
      "aliases": [
        "UBUNTU-CVE-2026-41070"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "openvpn-auth-oauth2",
            "purl": "pkg:deb/ubuntu/openvpn-auth-oauth2?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "1.27.0-2",
            "1.28.0-1",
            "1.28.3-2"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-41070.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "openvpn-auth-oauth2",
                "binary_version": "1.28.3-2"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "openvpn-auth-oauth2",
            "purl": "pkg:deb/ubuntu/openvpn-auth-oauth2?arch=source&distro=esm-apps%2Fresolute",
            "ecosystem": "Ubuntu:Pro:26.04:LTS"
          },
          "versions": [
            "1.27.0-2",
            "1.27.0-2ubuntu0.1~esm1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-41070.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "openvpn-auth-oauth2",
                "binary_version": "1.27.0-2ubuntu0.1~esm1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:54:54.163500748Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-41070"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-41070",
        "https://www.cve.org/CVERecord?id=CVE-2026-41070",
        "https://github.com/jkroepke/openvpn-auth-oauth2/security/advisories/GHSA-246w-jgmq-88fg",
        "https://github.com/jkroepke/openvpn-auth-oauth2/commit/36f69a6c67c1054da7cbfa04ced3f0555127c8f2"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-41070",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 353582,
  "published_at": "2026-05-08T16:16:00+00:00"
}