A vulnerability in eap-mschapv2 plugin allowing a malicious client to trick the server into successfully concluding the authentication without providing valid credential. The problem is caused by insufficient verification of the local state in the server implementation of the EAP-MSCHAPv2 protocol. In fact, the client can simply send the last message in the EAP-MSCHAPv2 protocol (an empty Success message) as response to the server's initial Challenge message to pass the authentication successfully. Affected are IKEv2 connections that use EAP-MSCHAPv2 to authenticate clients via eap-mschapv2 plugin. Affected are all strongswan versions 4.2.12, up to and including 5.3.3.
Created strongswan tracking bugs for this issue:
Affects: fedora-all [bug 1283220]
Affects: epel-all [bug 1283221]
This issue did not affect the versions of strongimcv as shipped with Red Hat Enterprise Linux 7, as they did not include support for the eap-mschapv2 plugin.