Authenticated command execution via CreateProcess quoting bypass
Published Sep 7, 2026 · Updated Sep 8, 2026
Argument injection 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 commands. OpenVPN passes certificate-subject fields to Windows batch validation hooks without neutralizing cmd.exe metacharacters or environment-variable expansion before CreateProcess runs the command line. Exploitation requires a configured validation script and a certificate issued by a rogue trusted CA; injected commands execute before the hook can reject the peer.
Summary
What happened
Argument injection 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 commands. OpenVPN passes certificate-subject fields to Windows batch validation hooks without neutralizing cmd.exe metacharacters or environment-variable expansion before CreateProcess runs the command line. Exploitation requires a configured validation script and a certificate issued by a rogue trusted CA; injected commands execute before the hook can reject the peer.
The record
- CVE
- CVE-2026-84256
- Published
- Sep 7, 2026
- Updated
- Sep 8, 2026
- Vendor
- OpenVPN Inc.
- Product
- OpenVPN
- Classifications
- CWE-88, T1059.003
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 7, 2026CVE publishedPublication date reported by the CVE source.
- Sep 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.1_rc10 <=2.6.22
- Affected versionversion=2.7_alpha1 <=2.7.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Windows batch-hook certificate-subject test caseproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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