strongSwan EAP-TTLS AVP Parsing Integer Underflow Vulnerability Leading to Denial-of-Service

An integer underflow vulnerability has been identified in the strongSwan VPN software, specifically in versions 4.5.0 prior to 6.0.5. This vulnerability resides in the EAP-TTLS AVP parser, where the absence of proper length validation allows unauthenticated remote attackers to send crafted AVP data during IKEv2 authentication. Exploitation of this flaw can cause excessive memory allocation or a NULL pointer dereference, leading to a crash of the charon IKE daemon.

Impact

Exploitation of this vulnerability can cause a denial-of-service condition by crashing the charon IKE daemon, which is responsible for handling IKEv2 negotiations and can disrupt active VPN connections.

Remediation

Users can upgrade to strongSwan version 6.0.5 or apply the available patch for older releases. The patch can be downloaded from the strongSwan security patch repository.