CVE-2026-84256

OpenVPN: OpenVPN: Arbitrary command execution via crafted certificate subject

Published Sep 7, 2026 CVSS 4.0 · 7.7 High EPSS < 1% KEV · Not listed
Description
An argument parsing issue in OpenVPN 2.1_rc10 through 2.6.22 and 2.7_alpha1 through 2.7.7 on Windows allows remote authenticated users to execute arbitrary commands via a crafted certificate subject

Analysis

AI-generated

Technical impact

OpenVPN versions 2.1_rc10 through 2.6.22 and 2.7_alpha1 through 2.7.7 for Windows contain an argument parsing issue that allows a remote authenticated user to execute arbitrary commands via a crafted certificate subject. This flaw reflects a command‑injection weakness (CWE‑78) and improper certificate subject handling (CWE‑88). If exploited, an attacker could run arbitrary code with the privileges of the OpenVPN server process, potentially compromising the host.

Affected Systems

The affected vendor is OpenVPN, product OpenVPN, and the impacted releases are the Windows builds of OpenVPN 2.1_rc10 through 2.6.22 and 2.7_alpha1 through 2.7.7. No other platforms or products are listed in the entry. Administrators should verify the exact version in use against these ranges to determine whether they are impacted.

Risk and Exploitability

The CVSS score of 7.7 indicates a high severity, while the EPSS score is listed as < 1%, showing that exploitation attempts are unlikely at the moment. The vulnerability is not recorded in CISA’s KEV catalog. An attacker must first authenticate to the VPN server and then provide a client certificate that contains a specially crafted subject field; if accepted, the vulnerable code will parse the subject and execute the embedded command within the OpenVPN server process context. Because the command runs under the server's privileges, successful exploitation can lead to full system compromise.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade to the latest OpenVPN version (2.6.23 or newer) that fixes the certificate subject parsing issue.
  • If an upgrade cannot be performed immediately, disable or restrict client certificate authentication on Windows installations until the patch is applied.
  • Continuously monitor VPN server logs for unexpected command executions and enforce strict certificate validation policies to detect and stop potential exploitation.

Generated by OpenCVE AI on October 17, 2026 at 09:51 UTC.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Description An argument parsing issue in OpenVPN 2.1_rc10 through 2.6.22 and 2.7_alpha1 through 2.7.6 on Windows allows remote authenticated users to execute arbitrary commands via a crafted certificate subject An argument parsing issue in OpenVPN 2.1_rc10 through 2.6.22 and 2.7_alpha1 through 2.7.7 on Windows allows remote authenticated users to execute arbitrary commands via a crafted certificate subject
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Openvpn
Openvpn openvpn
Vendors & Products Openvpn
Openvpn openvpn
Type Values Removed Values Added
Title OpenVPN: OpenVPN: Arbitrary command execution via crafted certificate subject
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Type Values Removed Values Added
Description An argument parsing issue in OpenVPN 2.1_rc10 through 2.6.22 and 2.7_alpha1 through 2.7.6 on Windows allows remote authenticated users to execute arbitrary commands via a crafted certificate subject
Weaknesses CWE-78
CWE-88
References
Metrics cvssV4_0

{'score': 7.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Weaknesses
  • CWE-78

    Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

  • CWE-88

    Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

Sources

Status
PUBLISHED
Assigner
OpenVPN
Published
Updated
Oct 13, 2026, 10:25 PM
Reserved
Sep 1, 2026, 1:36 PM
Status
Awaiting Analysis
Published
Sep 7, 2026, 8:17 AM
Modified
Oct 13, 2026, 11:18 PM
Severity
Important
Public date
Sep 7, 2026, 7:55 AM