5 Cyber Security Risks for UK Businesses in 2026

At the end of last year, we mapped out the cyber risks shaping 2026. Since then, we've watched them play out in real time, Jaguar Land Rover, Transport for London, the Department for Education, Marks & Spencer, Co-op, Harrods. Different companies, same five root causes.

Here's the uncomfortable truth: the hackers aren't smarter, they're just faster, with better tools. AI writes their phishing emails now. Your suppliers are their favourite backdoor. And your team's new favourite AI chatbot might be quietly leaking company data.

We've spent this year tracking real breaches, and they all boil down to five recurring risks. Here's what's actually putting UK businesses at risk in 2026, and what to do about each one.

The 5 cyber security risks for businesses in 2026

In short: AI-powered phishing and deepfakes, supply chain and third-party breaches, ransomware that targets backups directly, stolen credentials, and unsanctioned ("shadow") AI use by staff. Here's each one in detail, with a real 2026 breach behind it.

1. AI is writing better scams than your staff can spot

Forget the classic phishing email with bad spelling. AI now writes flawless emails, clones voices, and can fake video calls convincingly enough to pass a second glance. A "call from IT support" asking to reset a password might really be an attacker with an AI-cloned voice, a trick behind several of this year's biggest breaches.

The catch: your team was trained to spot mistakes. AI doesn't make the mistakes anymore. Spelling and tone were never the real signal, verification was. That's the bit most training programmes skip.

What helps: move away from "spot the scam" training and toward "verify before you act" habits, a second channel check for any request involving money, passwords, or access, no exceptions for how urgent or senior the requester sounds.

2. Your weakest link might not even be you

Marks & Spencer, Co-op and Harrods weren't hacked through their own front doors, attackers phoned M&S's outsourced IT helpdesk, impersonated an employee, and talked their way into an MFA reset on a privileged account. From there, they had the keys to the kingdom. Separately, a single compromised integration on a popular CRM platform gave attackers a foothold across hundreds of organisations worldwide in one campaign.

We covered the retail attacks in detail here — worth a read if you want the full breakdown of how Scattered Spider operated.

The catch: you can lock down your own systems perfectly and still get breached through someone you trust; a supplier, an IT contractor, or a piece of software you didn't even know was connected to your network.

What helps: a clear, current view of which third parties and integrations can reach your systems, and ongoing monitoring rather than a one-off check at onboarding. This is exactly what attack surface management is built for, visibility into the connections you've forgotten about.

3. Ransomware now goes for your safety net first

Ransomware used to lock your files and demand payment. Now it deletes your backups first, so restoring and walking away isn't an option. Jaguar Land Rover found out the hard way: five weeks of production stopped cold, an estimated £1.9 billion hit to the UK economy according to the Cyber Monitoring Centre, and more than 5,000 organisations affected across its supply chain, no ransom even needed to be paid to cause that scale of damage.

The catch: a backup that can be deleted alongside your live systems isn't really a backup.

What helps: backups that are genuinely isolated from your production network, tested restore drills (not just "we have backups" on a slide), and a rehearsed incident response plan so the first time your team handles a live incident isn't the day it actually happens. We've written before about why a good response plan matters more than who gets blamed.

4. Stolen logins are still the easiest way in

Phishing, credential stuffing, or simply buying passwords off the dark web, stolen logins remain one of the simplest ways into a business. And once an attacker's in with real credentials, they don't look like a hacker. They look like an employee.

The catch: MFA helps, but attackers are learning to talk their way past it by targeting help desks directly, not by trying to crack it, the same playbook behind the M&S breach above.

What helps: test this specifically, don't assume it. A red team engagement that includes a help desk social engineering attempt will tell you in an afternoon whether your process would hold up to the exact trick that took down a FTSE 100 retailer.

5. Your staff's favourite AI tool might be leaking your data

Employees are pasting customer details, contracts, and financial data into AI chatbots to save time, often without telling anyone. It's not malicious, it's just faster. But it's also a brand-new way for sensitive data to walk out the door.

The catch: this risk barely existed two years ago, and most security policies haven't caught up. Verizon's 2026 Data Breach Investigations Report found that the share of employees regularly using AI tools on corporate devices (authorised or not) jumped from 15% to 45% in a single year. Shadow AI is now the third most common non-malicious insider action showing up in breach data, a fourfold increase on the year before.

What helps: clear, specific rules on which AI tools staff can use and what they can and can't feed into them, and visibility into what's actually running across your environment, since you can't govern what you can't see. Again, this is where attack surface management earns its keep: it surfaces the unsanctioned tools and shadow IT that policy alone won't catch.

So, what actually helps?

No single tool fixes all five. But a few things move the needle for every business, regardless of size:

• Test your people, not just your firewalls, including how your help desk handles a suspicious password reset request

• Treat supplier and integration access as an ongoing risk, not a box ticked at onboarding

• Make sure your backups actually work when you need them, not just that they exist

• Set clear rules on which AI tools staff can use, and what they can and can't feed into them

  
  

The businesses that stay off next year's breach list aren't the ones with the biggest budgets. They're the ones who find their own weak spots before someone else does.

Want a clearer picture of where yours are? Book a consultation with One Compliance and we'll help you find them before an attacker does.

FAQs

What are the biggest cyber security risks facing businesses in 2026? AI-powered phishing and deepfake scams, supply chain and third-party breaches, ransomware attacks that target backups directly, stolen credentials, and unsanctioned ("shadow") AI use by staff. Together these five account for the majority of major UK breaches this year.

How does ISO 27001 address modern threats like phishing and deepfakes? ISO 27001 doesn't name specific attack methods, but its risk assessment and incident response requirements force organisations to identify current threats (including AI-driven social engineering) and put controls and response plans in place around them. It's a framework for staying current, not a fixed checklist. Read more about our ISO 27001 support.

What's the biggest cyber security risk for large enterprises right now? Supply chain exposure. Large organisations typically have dozens or hundreds of third-party integrations and suppliers, any one of which can become the entry point, as seen with the M&S, Co-op and Harrods breaches, all traced back to a single compromised help desk process.