A high-severity Denial of Service vulnerability in FRRouting allows unauthenticated remote attackers to crash routing services via malformed OSPF traffic.

The software contains a NULL pointer dereference within the show_vty_ext_link_lan_adj_sid function located in ospf_ext.c. This flaw permits an unauthenticated attacker to trigger a crash of the routing daemon by sending a specially crafted OSPF packet to the target system.

Successful exploitation of this vulnerability leads to a complete Denial of Service for the affected routing instance. Given that FRRouting is frequently deployed in critical network infrastructure, a crash can result in significant network outages, traffic disruption, and loss of connectivity for downstream services. With a CVSS score of 7.5, the risk is classified as High due to the ease of remote exploitation and the lack of required authentication.

Immediate Action: Administrators should monitor the official FRRouting repository for the release of a patched version and apply updates as soon as they become available.

Proactive Monitoring: Security teams should monitor OSPF traffic for malformed packets or unusual spikes in protocol-specific traffic that may indicate attempted exploitation.

Compensating Controls: Implement network-level access control lists (ACLs) to restrict OSPF peering to trusted, authenticated neighbors only, which can prevent unauthorized packets from reaching the vulnerable function.

Public Exploit Available: Yes, a technical write-up containing attack details exists at the provided BugList reference.

This vulnerability poses a significant risk to network availability and must be prioritized for remediation. Organizations should verify their current FRRouting version and prepare to deploy the forthcoming patch immediately upon release to prevent potential service disruption.