What You Need To Know About Buffer Overflow Attacks

Written by: Lizzie Danielson
Published: 6/9/2026

From the Morris Worm in 1988 to the WannaCry outbreak in 2017, buffer overflow attacks are a persistent cybersecurity threat. Recent critical vulnerabilities continue to show this problem isn’t going away anytime soon.

These aren’t just glitches that crash an app. They can give a hacker the keys to your system, allowing them to move throughout your network or deploy ransomware.

In this guide, we’ll explain how these breaches work and why behavioral detection is your best defense.

Key Takeaways

Buffer overflow is a decades-old security flaw where threat actors overwhelm program memory by inputting too much data.
This security issue remains a threat since modern systems still use memory-unsafe languages that threat actors work around.
Secure coding, OS-level protections, and patching are three common ways to address buffer overflow, but they aren’t enough.
Behavior-based endpoint detection adds a necessary layer of security to catch the malicious activity that follows buffer overflow exploits and other memory-safety bugs.

What’s a buffer overflow?

A buffer overflow attack happens when a program receives more data than it can hold. The storage (buffer) is a fixed-size block of memory meant to hold limited information. When it overflows, that data spills into nearby areas.

In a normal situation, this overflow just causes a segmentation fault. But a threat actor can use it to overwrite critical instructions and hijack a system. Your system.

Programming languages used to build system software are common targets due to their lack of built-in bounds checking. “Memory-safe” programming languages like Rust or Go use bounds checking to keep software from accessing data outside of its designated area (or “bounds”).

For these reasons, CISA flags reliance on memory-unsafe languages like C and C++ for new internet-facing software as a “bad practice” in its product security guidance.

Crashing a process isn’t the end goal. Threat actors use buffer overflows to gain code execution and escalate privileges so they can take control of systems and move deeper into your environment.

How AI comes into play

New AI models are getting better at spotting software vulnerabilities. In the right hands, these tools help companies improve their security. In the wrong ones, AI can find more ways into systems with less effort.

Recently, Anthropic researcher Nicholas Carlini used a basic script to ask Claude Code to search for vulnerabilities in the Linux kernel. The tool found a buffer flow exploit that’s been in place since 2003. Linux has since issued patches, but the discovery raises concerns: What exploits are still out there waiting for AI to surface them?

Types of buffer overflow attacks

All buffer overflow attacks are slightly different, and an attacker needs to use various methods based on where the data spilled happened. While some are easy to pull off, others need real technical skill.

Stack-based buffer overflow

A stack buffer overflow happens in a part of computer memory that uses a “last-in, first-out” approach to organize code. This fast, automatically managed part of storage is the stack.

Think of the stack like a pile of trays. At the bottom of each tray is a return address. In computer terms, this is a note telling the computer where to go next after it’s done with a task. In a stack buffer overflow, a hacker sends enough data to overwrite that note. So, instead of going back to normal work, the computer follows the new and malicious instructions to run the hacker’s shellcode.

Cybersecurity experts built tools to block this, but threat actors simply adapted. Threat actors now use tricks like return-oriented programming (ROP) or jump-oriented programming (JOP) to sneak in. Instead of bringing their own malware, they chain together tiny pieces of legitimate code already in your system. When it’s ready, the code is repurposed to do the attacker’s dirty work.

This style of overflow was used for the EternalBlue exploit, which later fueled the WannaCry ransomware attack.

Heap-based buffer overflow

A heap overflow attack targets the large, dynamic area of memory used for long-term data. This flexible part of storage is the heap.

Unlike the stack, there’s no simple return address in a heap attack. Instead, attackers need to corrupt the underlying memory structures or metadata the system uses for organization. If done right, threat actors gain full control or escalate their privileges in your system.

Off-by-one overflow

Threat actors don’t always need a massive flood of data to take advantage of a buffer overflow vulnerability. Sometimes, they just need a single extra character.

An off-by-one overflow happens when a programmer makes a tiny math error, like forgetting the null terminator at the end of a string in C. While it sounds trivial, that one-byte overwrite can sneak into control data and redirect execution.

Unlike stack-based or heap-based overflows, this kind of bug is a reminder that software security isn’t always about flashy zero-days or intricate exploit chains—small off-by-one mistakes can be just as dangerous. For example, we’ve seen critical real-world issues like the WS_FTP vulnerabilities stem from subtle input handling flaws.

Real-world buffer overflow examples

You won’t have to look far to find a real-life buffer overflow example. Here are some of the most notable and widespread attacks since the 1980s:

The Morris Worm in 1988 used a buffer overflow attack to spread across 6,000 computers in the span of 24 hours. This incident marked the first major internet worm attack.
The WannaCry attack, or CVE-2017-0144, targeted a vulnerability in Windows SMBv1. It allowed ransomware to automatically spread across networks without anyone clicking a link, leading to issues with global shipping lines and hospitals.
Baron Samedit, or CVE-2021-3156, used a heap overflow attack that gave local users root access on Linux systems without needing a password. The vulnerability stayed hidden for years before the Qualys Research Team found it.
The CVE-2025-32756 stack overflow allowed an attacker to run malicious code just by sending a bad HTTP request. First discovered in 2025, this proved that buffer overflows weren’t a legacy problem.
Buffer overflow attacks are an ongoing threat in the cybersecurity world. As often as companies create a fix, threat actors seem to find a new vulnerability.

How to prevent buffer overflow attacks

Effective buffer overflow prevention calls for a layered approach, but relying on technology alone isn’t enough.

Here are best practices for stopping buffer overflow in its tracks.

Secure coding & memory-safe languages

The best way to stop an overflow? Prevent it during development. When writing new code, make sure to use memory-safe language with build-in bounds checking.

For legacy C/C++ apps, developers should replace unsafe functions like strcpy (copies text without checking size) with safer alternatives like strncpy (copies text with a size limit). This simple boundary requires input data to fit inside the fixed limits to keep threat actors out of the application.

If this isn’t a possibility, apply other security measures like stack canaries, address space layout randomization (ASLR), and data execution prevention (DEP) to make exploiting your environment difficult for threat actors.

OS-level runtime protections

Modern operating systems use a few tricks to make overflow exploits less likely:

Address space layout randomization (ASLR) scrambles memory addresses so attackers can’t find their target.
Data execution prevention (DEP) marks certain areas as nonviable to stop malicious code from running.
Structured exception handler overwrite protection (SEHOP) stops threat actors from adjusting the way a program handles errors.
While these are essential defenses, they aren’t foolproof. Highly skilled threat actors can still find workarounds with ROP and JOP tricks.

Patching (& why it’s not enough on its own)

Patching is your first line of defense, but it’s a reactive approach. In other words, it’s a response to someone finding a vulnerability before developers patch the problem. There’s always a window of risk during the time between discovering the vulnerability and installing the fix.

Once a hacker triggers an attack, traditional tools often miss the subtle process changes that follow. This is where lean security teams face their biggest gap: They can see the crash, but they can’t stop the hacker moving through their network.

How Huntress Managed EDR detects what patching misses

Security gaps pose a big problem when an experienced threat actor comes along. WIth no new binary or signature to catch, scanners can miss ROP and JOP tactics entirely.

That’s where behavioral detection comes in.

Huntress Managed EDR continuously monitors endpoint processes and activity in real time. Our 24/7 AI-centric SOC analysts review high-fidelity detections for malicious process behavior, persistence mechanisms, privilege escalation, and lateral movement—not just obvious malware files.

When we detect suspicious activity, our Managed EDR Attack Disruption Engine can automatically kill malicious processes, stop suspicious code execution, and block new footholds while sending an accelerated alert to our SOC.

Find out how Huntress can help protect your system against buffer overflows and other behavioral-based attacks. Start your free trial today.

FAQs

A buffer overflow is the broad category of an attack based on overloading a program’s memory. A stack overflow is a type of buffer overflow attack that happens in the stack region.

Yes, buffer overflow is still a problem in 2026. Threat actors continue to exploit this security gap because legacy systems still use C and C++. Even programs written in safer languages don’t have a foolproof prevention method.

Once a threat actor successfully exploits a buffer overflow, they can often execute arbitrary code, escalate privileges, and take effective control of the affected system.

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What You Need To Know About Buffer Overflow Attacks

Key Takeaways

What’s a buffer overflow?

How AI comes into play