# CVE-2026-13698 - Server memory leak via repeated tls-crypt-v2 HARD_RESET_CLIENT_V3 packets

A memory leak in the `tls_crypt_v2_extract_client_key` function in OpenVPN 2.x allows remote attackers with a valid
tls-crypt-v2 client key to cause a denial of service (memory exhaustion) via repeated `HARD_RESET_CLIENT_V3` packets
when `tls-crypt-v2` is enabled because the server fails to free existing key contexts before overwriting them during
session re-initialisation.

OpenVPN version 2.5.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 are affected. This is fixed in versions 2.6.21 and 2.7.5.

CVE Record: [CVE-2026-13698](https://www.cve.org/CVERecord?id=CVE-2026-13698)

Github:
* [OpenVPN/openvpn-private-issues#137](https://github.com/OpenVPN/openvpn-private-issues/issues/137)

Release notes:
* [openvpn-2.7.5](https://community.openvpn.net/ReleaseHistory#openvpn-275-released-1-july-2026)
* [openvpn-2.6.21](https://community.openvpn.net/ReleaseHistory#openvpn-2621-released-1-july-2026)

Reported-By: Max Fillinger (maximilian.fillinger@sentyron.com)