Memory corruption and disclosure via NRPT size miscalculation
Published Sep 7, 2026 · Updated Sep 8, 2026
Incorrect buffer sizing in OpenVPN 2.7_alpha1 through 2.7.6 on Windows allows local users to corrupt memory or disclose sensitive information. Openvpnserv assumes that the NRPT domain list contains only ASCII characters and passes the wrong size after converting UTF-8 IDN domains, causing an overread that writes extra data to the Windows Registry. Exploitation requires local authenticated access and crafted NRPT input; the overread can corrupt service memory or expose adjacent data through the registry.
Summary
What happened
Incorrect buffer sizing in OpenVPN 2.7_alpha1 through 2.7.6 on Windows allows local users to corrupt memory or disclose sensitive information. Openvpnserv assumes that the NRPT domain list contains only ASCII characters and passes the wrong size after converting UTF-8 IDN domains, causing an overread that writes extra data to the Windows Registry. Exploitation requires local authenticated access and crafted NRPT input; the overread can corrupt service memory or expose adjacent data through the registry.
The record
- CVE
- CVE-2026-78221
- Published
- Sep 7, 2026
- Updated
- Sep 8, 2026
- Vendor
- OpenVPN Inc.
- Product
- OpenVPN
- Classifications
- CWE-131
- Attack vector
- local
- 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=2.7_alpha1 <=2.7.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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