In strongSwan before 5.9.5, a malicious responder can send an EAP-Success message too early without actually authenticating the client and (in the case of EAP methods with mutual authentication and EAP-only authentication for IKEv2) even without server authentication.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-45079
• https://www.strongswan.org/blog/2022/01/24/strongswan-vulnerability-(cve-2021-45079).html