2025 in Review: The Cyber Incidents That Redefined Risk and Resilience

When you think about a forward-thinking organisation from a tech perspective, you’ll probably think of how they do things like continue to strive for digital transformation, scale, and uptime. You might even recognise that there’s a constant push for continued investment to help steer them along their journey.

Whatever they settle on, whether it’s AI, state-of-the-art firewalls, a migration to the cloud, or even a DMARC deployment, they do so to provide the best possible platform for the business to securely grow from.

On the other side of that same coin, though - and part of the reason for continued investment - is cyber attackers. And they’re just as relentless in their pursuit of continued improvement. They’re continuously probing, pivoting, and trying new (or in some cases, tried and tested) methods to exploit weaknesses in your defence. And the bad news is, they were successful.

So much so that it could be argued that if there was one constant across 2025, it was this: cyber risk never paused.

What started as isolated headlines has become a series of systemic reminders that resilience cannot be an afterthought.

The year just gone delivered a suite of real-world incidents that illustrate this, with some affecting consumer services and left users frustrated, while others cut into national infrastructure or corporate supply chains with costly implications, with one going down as the most costly cyber incident in UK history (to date).

What ties them all together isn’t the industry they target, or the methods they deploy, but rather the lessons they teach.

So, with the year in our rearview mirror, we’re taking a look back at some of the key incidents of 2025, what they reveal about modern cyber risk, and how those lessons must shape the year ahead.

A Year of High-Profile Disruption

Cloudflare’s November Outage and the Fragility of Edge Dependencies

On the 18th of November, Cloudflare (one of the internet’s most ubiquitous edge and DNS providers) experienced a major outage that rippled across customers worldwide. Systems that depended on Cloudflare for traffic routing, authentication, and security suddenly found themselves unreachable or unstable.

It’s important to preface that this wasn’t a classic “hack”, but initial fears online did go toward ‘what if..’ territory. What actually happened was a failure in a central service that thousands of organisations rely on to provide resilience. Our analysis in, What the November 2025 Cloudflare Outage Teaches Organisations About Resilience, highlights how upstream dependencies can themselves be a critical risk vector. Many organisations discovered that redundancy and critical path visibility were weaker than assumed.

If that wasn’t enough of a lesson, it suffered a second outage on the 5th December, to really hammer home the point. A lesson for 2026 is the evergreen bit of advice: don’t put all your eggs in one basket!

Lesson: Relying on a single provider or a monoculture infrastructure increases correlated risk.

The Cost of Not Investing in Security

Throughout 2025, incidents across almost every sector imaginable showed again and again that deferring investment in security, whether that be tools, process, or even people, invariably compounds costs. From ransomware to credential stuffing, the root cause in many breaches remained the same: inadequate preventative measures.

Our piece, The True Cost of Not Investing in Security, lays out the hard arithmetic many organisations ignore. The immediate loss from a breach is often only the start; follow-on impacts on operations, reputation, and the future cost of capital can vastly outweigh the original investment that was never made.

Lesson: Security isn’t a cost centre that disappears when budgets tighten. It’s insurance, and often, a differentiator.

Cloud Interdependence: When One Failure Spreads Far and Wide

The cloud was meant to deliver resilience, elasticity and a platform for your business to grow from. Yet, in 2025, multiple incidents demonstrated that cloud interdependencies can sometimes amplify, rather than mitigate, systemic risk.

In When the Cloud Sneezes, the Internet Catches a Cold, we explored how issues in shared services, APIs, routing layers, and orchestration tooling can propagate rapidly. Whether it was a bad configuration, an overloaded API, or an upstream misroute, these failures remind us that the cloud doesn’t absolve us of responsibility for resilience. It merely changes where and how those responsibilities are managed.

Lesson: Designing for failure isn’t just a best practice. It’s become an operational imperative.

Industrial and National Scale Impact: From Airlines to Automakers

2025 also saw attacks with broader societal impact. Systems that were once considered isolated became vectors for cascading disruption, and headlines that impacted thousands of us.

Our analysis of attacks on infrastructure, including the high-profile cases involving Heathrow disruptions and a major automaker, underscores this shift. In When the Wheels Stop Turning: What the JLR Cyberattack and Heathrow Shutdown Teach UK Businesses, we unpack how deeply interconnected systems mean that an attack or failure in one domain, or with one third-party, can paralyse adjacent sectors and supply chains.

Lesson: Modern business ecosystems are tightly coupled. A breach or outage in one area can have a multi-vector impact.

Gaming Platforms, Live Services and Holiday-Period Threats

2025 closed with another vivid reminder: attackers don’t align with human calendars. The breach affecting Rainbow Six Siege over the Christmas period wasn’t just a headline for gaming communities or those unpacking new gaming consoles or computers; it was a live case study in always-on risk. Emergency shutdowns and rollbacks followed once trust in live systems was compromised.

This incident, like many others this year, shows that when teams are thinner, monitoring is reduced, and response paths are slower, the attack surface effectively widens. Whether an MMO or a business-critical system, the dynamics are the same.

Lesson: Seasonal rhythm doesn’t reduce risk. If anything, it sharpens exposure.

Patterns That Emerged in 2025

Looking across these cases, a few clear themes come into focus:

1. Systemic Interdependence

Whether it’s the cloud, DNS providers, or connected service stacks, organisations are part of broader ecosystems. Failure in a dependence, even one outside your direct control, is a risk you must plan for.

2. Preparedness Beats Prevention Alone

Unfortunately, not all incidents can be prevented anymore. But what differentiates organisations that recover from those that suffer long-lasting harm is the strength of their preparedness: monitoring, incident response practice, clear escalation paths, and tested rollback/recovery procedures.

3. Visibility Matters

Several incidents this year were exacerbated by limited observability. If an attack or failure goes unnoticed or is slow to be detected, the impact expands. Telemetry, logging, anomaly detection, and alerting must be real-time and actionable.

4. Human Element Remains Central

Automated tooling is necessary, but people still make the difference (even though they can be the easiest way through state-of-the-art defences). Decisions during an incident, such as coordination across teams, clear communication, and measured rollback, all rely on well-practised human processes.

Looking Ahead to 2026

If 2025 taught us anything, it is that complexity and connectivity will continue to grow. The expanding attack surface isn’t a phase; it’s the operating environment.

In 2026, organisations must move from reactive resilience to proactive adaptability. This means:

• Designing systems that tolerate failure gracefully.

• Running frequent, realistic incident exercises.

• Investing in visibility and telemetry that outpace the dwell time of attackers.

• Rooting security choices in measurable risk outcomes, not checkbox compliance.

• Anticipating supply-chain and dependency risk as core business risk.

Next week, we’ll take a deeper look at what 2026 will bring in threat trends, resilience strategies, and how organisations can pivot from surviving cyber risk to mastering it.

For now, if there’s one takeaway from the last year, it is this: resilience is not a destination. It is a discipline.