Risks from Legacy and Unpatched Systems in Critical Infrastructure

A new Cisco report highlights the growing risk posed by legacy and unsupported systems within national critical infrastructure, revealing that nearly half of global business network assets were already aging or obsolete as of 2020. The United Kingdom, in particular, faces significant exposure, with 228 legacy systems identified across government in 2024 and over a quarter at high risk of operational or security failure. The report underscores that unsupported systems, often located at network edges, are prime targets for attackers, and that a majority of breaches in the EU during 2022 and 2023 exploited vulnerabilities with available but unapplied patches. Healthcare and other essential sectors are especially vulnerable due to concentrated use of outdated technology.

Recent cyberattacks have increasingly targeted legacy firewalls and network devices, with state-sponsored groups exploiting known vulnerabilities in products from vendors such as Cisco, SonicWall, Palo Alto Networks, and Fortinet. Research indicates that 60% of enterprise firewalls fail high-severity compliance checks, reflecting deeper governance and patch management issues. Attackers are leveraging these weaknesses, often chaining exploits across network edges and VPNs, while defenders struggle with fragmented vendor alerts and outdated risk frameworks. The persistent use of unsupported technology and delayed patching continues to undermine national resilience and exposes critical infrastructure to significant cyber threats.