PatchSiren cyber security CVE debrief
CVE-2026-40215 OpenVPN CVE debrief
CVE-2026-40215 is a medium-severity vulnerability in OpenVPN, allowing remote attackers to potentially cause a server crash or leak heap memory via a use-after-free triggered during TLS session promotion. The vulnerability affects OpenVPN versions 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1.
- Vendor
- OpenVPN
- Product
- Unknown
- CVSS
- MEDIUM 6.1
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-06-08
- Original CVE updated
- 2026-06-09
- Advisory published
- 2026-06-08
- Advisory updated
- 2026-06-09
Who should care
Users of OpenVPN versions 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1 should be aware of this vulnerability and take necessary actions to mitigate the risk.
Technical summary
A race condition in OpenVPN 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1 allows remote attackers to potentially cause a server crash or leak heap memory via a use-after-free triggered during TLS session promotion.
Defensive priority
Medium
Recommended defensive actions
- Update to a fixed version of OpenVPN
- Refer to [ref-6](https://community.openvpn.net/Security%20Announcements/CVE-2026-40215) for security announcements and patches
Evidence notes
The CVE record [cve-org] and NVD detail [nvd] provide official information about the vulnerability.
Official resources
CVE-2026-40215 was published on 2026-06-08T21:16:45.453Z and modified on 2026-06-09T02:08:28.150Z.