We all remember when “technical debt” became the buzzword of the software world. It was the term developers used to explain why things were starting to slow down, why releases were taking longer, why systems were creaking under the weight of shortcuts made in the name of speed.

Now, a decade on, a new kind of debt is quietly piling up. And it’s arguably more dangerous.

Security debt is what happens when unresolved vulnerabilities, forgotten assets, outdated configurations, and rushed deployments are left to fester. It’s the legacy of decisions made in a hurry, often with good intentions, to hit a launch date, to keep pace with innovation, or to sidestep bureaucracy just long enough to deliver something meaningful.

But just like technical debt, security debt does not stay silent forever.

The problem is that most of this risk is invisible until it’s too late. That unmonitored subdomain from a discontinued campaign? A perfect target for subdomain takeover. That unused SaaS account from three years ago? It may still hold sensitive data and be accessible with a reused password. Those misconfigured cloud buckets? They're exactly what attackers are scanning for.

When organisations move fast, they often create blind spots, and attackers thrive in blind spots.

What makes security debt especially dangerous is that it is easy to justify. Teams tell themselves they’ll tidy it up later. They assume something that’s out of sight is also out of reach. Or they rely on traditional security tools that are simply not designed to surface these kinds of risks. Firewalls, antivirus software, and compliance scanners are all essential, but they don’t see what’s happening outside your perimeter. They don’t know about the marketing microsite set up two years ago and never shut down. They don’t know about the dev team’s temporary S3 bucket that became permanent through neglect.

The shift to remote work, cloud-first strategies, and rapid digital transformation has supercharged this problem. Security is no longer just about hardening the walls around your infrastructure. It’s about knowing what you’ve exposed to the internet, even accidentally, and ensuring it is either locked down or removed entirely.

This is where modern approaches like External Attack Surface Management (EASM) come in. EASM gives security teams continuous visibility into what an attacker can see and target. It acts like a searchlight, cutting through the fog of forgotten infrastructure and rogue IT. Combined with continuous threat monitoring, it allows organisations to address problems proactively rather than reactively.

So what can you do about it?

Start with inventory discipline. If you don’t know what you own, you can’t protect it. This includes cloud assets, SaaS accounts, exposed APIs, expired domains, all of it.

Next, prioritise remediation. Not every vulnerability needs to be fixed immediately, but the ones with clear paths to exploitation should never wait.

Invest in tools that help you maintain real visibility into your attack surface. Platforms like DarkInvader are built specifically for this purpose, helping you see what attackers see and act before they do.

And finally, think culture. Just like DevOps encouraged a shift-left mindset in development, we need to embed security thinking early, not treat it as something bolted on later. That means bringing security conversations into planning meetings, sprint reviews, and product retros. It means rewarding teams not just for what they build, but how safely they build it.

Because security debt, like any debt, compounds. The longer you leave it, the harder and more expensive it is to deal with. But with the right visibility, mindset, and tooling, you can break the cycle.

And when the next breach headline hits the news, you can breathe a little easier knowing you haven’t left the door wide open.