Authenticated identity bypass via ignored X.509 field
Published Aug 14, 2026 · Updated Aug 14, 2026
Improper certificate validation in OpenVPN 2.7_alpha1 through 2.7.5 allows remote authenticated users to assume an unintended identity. The mbedTLS backend's backend_x509_get_username function used the certificate common name instead of the field selected by --x509-username-field. Exploitation requires an mbedTLS build, that nondefault option, and a CA-signed certificate whose common name matches an identity the server permits.
Summary
What happened
Improper certificate validation in OpenVPN 2.7_alpha1 through 2.7.5 allows remote authenticated users to assume an unintended identity. The mbedTLS backend's backend_x509_get_username function used the certificate common name instead of the field selected by --x509-username-field. Exploitation requires an mbedTLS build, that nondefault option, and a CA-signed certificate whose common name matches an identity the server permits.
The record
- CVE
- CVE-2026-63650
- Published
- Aug 14, 2026
- Updated
- Aug 14, 2026
- Vendor
- OpenVPN Inc.
- Product
- OpenVPN
- Classifications
- CWE-115, CWE-295, T1078
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 14, 2026CVE publishedPublication date reported by the CVE source.
- Aug 14, 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
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
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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