CVE-2014-0677

Vulnerability

The Label Distribution Protocol (LDP) functionality in Cisco NX-OS contains a vulnerability that allows an unauthenticated, remote attacker to cause a temporary denial of service. By sending LDP discovery traffic containing a malformed Hello message, the attacker can trigger a temporary outage of the LDP session. This issue is documented as Bug ID CSCul88851 and affects Cisco NX-OS systems running LDP.

Exploitation

An attacker does not need any authentication or special network access beyond being able to send LDP discovery packets to the targeted device. The attack is carried out by crafting a malformed LDP Hello message and sending it to the target. The malformed message causes the target to temporarily drop the LDP session, disrupting ongoing label distribution operations.

Impact

Successful exploitation results in a temporary denial of service (DoS) of the LDP session. This outage disrupts MPLS label distribution, potentially affecting MPLS-based services such as VPNs and traffic engineering. The session typically recovers after the trigger, but repeated attacks can cause sustained disruption.

Mitigation

Cisco has not released a software update for this specific issue as of the publication date of the advisory (2014 January 22). Administrators are advised to monitor the Cisco Security Advisory for updates [1]. No workaround is mentioned in the available references. If no fix is released, the vulnerability remains unpatched.