Snyk Learn
learn.snyk.io › home › security education › use after free vulnerability | tutorial & examples
Use after free vulnerability | Tutorial & Examples | Snyk Learn
September 28, 2023 - Use after free (UAF) is a type of bug that can be exploited in programming languages that are not memory-safe. In C++, a developer is responsible for allocating (and deallocating) memory on either the stack or the heap.
Huntress
huntress.com › cybersecurity-101 › topic › what-is-use-after-free
Use-After-Free Explained: Master the Basics and Stay Secure | Huntress
A use-after-free vulnerability happens when an application tries to use memory it has already released or "freed." This type of bug can open the door for attackers to take control of programs, steal data, or crash critical systems.
Why is use after free error is so common?
usually there are two pointers involved. One part of the code has its pointer and frees whatever it points at, then another part of the code uses its copy to access the now freed memory. If the first part sets its copy to NULL it doesn't change any other copies of the pointer that are somewhere else. More on reddit.com
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May 25, 2025How can "use after free" exploit lead into execution of code?
if the memory has been previously freed, you are now ok to write it by allocating your own objects (heap spray). if you can overwrite a function pointer within the old object i.e. the vtable for a C++ object, you can then cause arbitrary code execution when the object is next used and the function pointer is called. More on reddit.com
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June 18, 2020Automated Use-After-Free Detection and Exploit Mitigation: How Far Have We Gone
An interesting read. It is nice to see more and more safety focus being added by the C++ community. This was seriously lacking ~2005->2015 and shows in many middleware libraries today. Many still refuse to use *any* smart pointer library, let alone that introduced to std ~C++0x / TR1. Even something as minimal as the following is very difficult to detect with static analysis and yet could easily result in a use-after-free. void Bomb::explode(std::shared_ptr& _self) { _self = std::make_shared(); m_name = "Booom"; } 99% of these issues could be mitigated if shared_ptr operator -> and * would increase reference count for the duration of access. Same with vector operator[] and iterator. Obviously this would cause overhead in terms of atomic incrementing ref count. However it would *still* be potentially faster than Java / CSharp.NET so whilst it wont replace high performance C++, it could replace switching language entirely. The fact that the OP paper even mentions Rust as upcoming shows that C++ has some rough edges in this regard. More on reddit.com
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October 27, 2021This memory safety issue everyone's talking about... It's not really a huge deal in gamedev, right? What other domains where C++ excels at aren't too concerned about it?
In embedded, memory issues are important. But the need to access physical hardware means lots of language protection just must be circumvented or the device ends up safe but broken - not doing "unsafe" memory accesses means the device will not do anything. At all. With C++, the selected design greatly decides if a program will be memory-safe or not. No need to code as if it's C from 1970. More on reddit.com
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September 29, 2023How serious are use-after-free vulnerabilities?
Very serious. MITRE ranked use-after-free as the fourth most dangerous software weakness in 2024. These vulnerabilities frequently lead to remote code execution with elevated privileges, making them high-priority targets for both attackers and patch management teams.
automox.com
automox.com › blog › vulnerability-definition-use-after-free
What Is a Use-After-Free Vulnerability? | Automox
Why are use-after-free vulnerabilities dangerous?
They allow attackers to hijack the flow of software, execute arbitrary code, access sensitive information, or cause crashes.
huntress.com
huntress.com › cybersecurity-101 › topic › what-is-use-after-free
Use-After-Free Explained: Master the Basics and Stay Secure | Huntress
What is a use after free vulnerability?
Use after free (UAF) is a type of bug that can be exploited in programming languages that are not memory-safe. In C++, a developer is responsible for allocating (and deallocating) memory on either the stack or the heap. While memory on the stack is statically allocated, memory on the heap can be dynamically allocated and deallocated.
learn.snyk.io
learn.snyk.io › home › security education › use after free vulnerability | tutorial & examples
Use after free vulnerability | Tutorial & Examples | Snyk Learn
Videos
10:59
Introduction to Use-After-Free Vulnerabilities | UserAfterFree ...
36:09
Understanding & explaining Use-After-Free vulnerability, a critical ...
14:59
Use After Free Vulnerabilities Demystified - YouTube
17:30
Exploiting a Use-After-Free (UAF) Vulnerability ...
Vulnerabilities 1002: 04 Use-After-Free CVE-2020-2674📦 02 ...
Vulnerabilities 1002: 04 Use-After-Free 01 Overview
MITRE
cwe.mitre.org › data › definitions › 416.html
CWE-416: Use After Free - Common Weakness Enumeration
A community-developed list of SW & HW weaknesses that can become vulnerabilities
Medium
expl0it32.medium.com › demystifying-use-after-free-vulnerabilities-a-deep-dive-into-memory-safety-issues-78ee7f8d44c2
Demystifying Use-After-Free Vulnerabilities: A Deep Dive into Memory Safety Issues | by eXpl0it_32 | Medium
April 23, 2025 - A Use-After-Free (UAF) vulnerability arises when a program continues to access memory that has already been deallocated (freed). This happens in low-level languages like C or C++, where developers are responsible for managing memory manually.
Automox
automox.com › blog › vulnerability-definition-use-after-free
What Is a Use-After-Free Vulnerability? | Automox
Track CISA's Known Exploited Vulnerabilities (KEV) catalog for UAF entries. When a CVE lands on this list, it means confirmed exploitation in the wild, and federal agencies are required to patch within a specified timeline. Set pointers to null after freeing memory. This is the most straightforward prevention. A null pointer dereference will crash the program, which is preferable to silent exploitation. Use smart pointers.
White Knight Labs
whiteknightlabs.com › 2025 › 06 › 03 › understanding-use-after-free-uaf-in-windows-kernel-drivers
Understanding Use-After-Free (UAF) in Windows Kernel Drivers | White Knight Labs
June 3, 2025 - The driver attempts to access memory (wrenchData) that has already been freed, leading to invalid memory access, which could cause memory corruption, system instability, or a BSOD.
Kaspersky IT Encyclopedia
encyclopedia.kaspersky.com › glossary › use-after-free
What is Use-After-Free? | Kaspersky IT Encyclopedia
February 18, 2026 - If a data set is deleted or moved to another block but the pointer, instead of being cleared (set to null), continues to refer to the now-freed memory, the result is a dangling pointer. If the program then allocates this same chunk of memory to another object (for example, data entered by an attacker), the dangling pointer will now reference this new data set. In other words, UAF vulnerabilities allow for code substitution. Potential consequences of UAF exploitation include: ... Arbitrary code execution. An attacker can use UAFs to pass arbitrary code — or a reference to it — to a program and navigate to the beginning of the code by using a dangling pointer.
Firewalls.com
firewalls.com › home › use after free (uaf)
Use After Free (UAF) - Firewalls.com
November 25, 2019 - This can cause crashes and data ... code execution capabilities. Types of use after free vulnerabilities have often been associated with web browsers such as Google Chrome and Mozilla Firefox, allowing for multiple successful attacks over a number of years....
Linux Security
linuxsecurity.com › features › what-is-a-use-after-free-uaf-vulnerability
Use After Free Vulnerability in Linux Servers: Risks and Mitigation
August 14, 2025 - CVE-2016-2107: A UAF vulnerability in OpenSSL was exploited during decryption, leading to a devastating padding oracle attack. CVE-2018-5333: UAF in ALSA (Advanced Linux Sound Architecture) that exposed systems to arbitrary code execution. CVE-2021-22555: A highly sophisticated UAF in Netfilter, which attackers leveraged to escalate privileges on Linux containers. Exploiting a use after free vulnerability is rarely a one-step attack—it often requires finesse and an understanding of how the kernel handles dynamic memory.
Cyber Security News
cybersecuritynews.com › home › cyberpedia
What is Use-After-Free Vulnerability? - Impact and Mitigation
August 18, 2025 - The vulnerability manifests when a program deallocates a memory region using functions like free() in C or delete in C++, but subsequently attempts to access or manipulate the same memory location through dangling pointers. This creates a dangerous condition where the freed memory may have been reallocated for different purposes, leading to unpredictable program behavior. The following concise C code demonstrates the core mechanism of a use-after-free vulnerability:
Caticx
caticx.com › home › what is use-after-free vulnerability? impact and mitigation
What is Use-After-Free Vulnerability? Impact and Mitigation | Caticx
September 26, 2025 - A Use-After-Free (UAF) vulnerability occurs when a program continues to use a pointer to memory that has already been freed.
OWASP Foundation
owasp.org › www-community › vulnerabilities › Using_freed_memory
Using freed memory | OWASP Foundation
The use of previously freed memory can have any number of adverse consequences - ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw.
CQR
cqr.company › web-vulnerabilities › use-after-free-vulnerability
Use-After-Free vulnerability | CQR
The vulnerability arises from incorrect memory management in a program. When a program frees a block of memory, it typically marks the memory as free, allowing it to be reused later.
ACM Other conferences
dl.acm.org › doi › 10.1145 › 3607199.3607229
All Use-After-Free Vulnerabilities Are Not Created Equal: An Empirical Study on Their Characteristics and Detectability | Proceedings of the 26th International Symposium on Research in Attacks, Intrusions and Defenses
October 16, 2023 - Over the past decade, use-after-free (UaF) has become one of the most exploited types of vulnerabilities. To address this increasing threat, we need to advance the defense in multiple directions, such as UaF vulnerability detection, UaF exploit ...
PauBox
paubox.com › blog › what-is-a-use-after-free-bug
What is a use after free bug?
May 22, 2024 - Privilege escalation and code execution: In some cases, attackers can use the UAF vulnerability to execute their own malicious code with elevated privileges, granting them unprecedented control over the affected system. Denial of service: Successful UAF exploits can disrupt the normal operation of the targeted application, effectively denying service to legitimate users. Addressing use-after-free vulnerabilities requires an approach combining coding practices, testing, and proactive security measures.
IMDEA
software.imdea.org › ~juanca › papers › undangle_issta12_av.pdf pdf
Undangle: Early Detection of Dangling Pointers in Use-After-Free
no false negatives and uncovers that two use-after-free · vulnerabilities in Firefox were caused by the same dan-
Reddit
reddit.com › r/c_programming › why is use after free error is so common?
r/C_Programming on Reddit: Why is use after free error is so common?
May 25, 2025 -
Whenever I hear about a software vulnerability, most of the time it comes down to use after free. Why is it so? Doesn't setting the pointer to NULL would solve this problem? Here's a macro I wrote in 5mins on my phone that I believe would solve the issue and spot this vulnerability in debug build
#if DEBUG
#define NIL ((void*)0xFFFFFFFFFFFFFFFFUL)
#else
#define NIL ((void *)0)
#endif
#define FREE(BLOCK) do { \
#if DEBUG \
if (BLOCK == NIL) { \
/* log the error, filename, linenumber, etc... and exit the program */ \
} \
#endif \
free(BLOCK); \
BLOCK = NIL; \
} while (0)Is this approach bad? Or why something like this isn't done?
If this post is stupid and/or if I'm missing something, please go easy on me.
P.S. A while after posting this, I just realised that I was confusing use after free with double freeing memory. My bad
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usually there are two pointers involved. One part of the code has its pointer and frees whatever it points at, then another part of the code uses its copy to access the now freed memory. If the first part sets its copy to NULL it doesn't change any other copies of the pointer that are somewhere else.
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The problem comes when you have more than one reference to an object, you call free on one of those references, set it to NULL and it’s all good, but you don’t have any way to find, or even know, what the other references could be that still point to the now freed object.
UDSpace
udspace.udel.edu › bitstreams › a36780f4-303e-4b05-8d04-de6bf4b3b28c › download pdf
AN EMPIRICAL STUDY ON USE-AFTER-FREE VULNERABILITIES by Benjamin P. Steenkamer
In relation to UAF vulnerabilities, an attacker can cause a DoS by making a · dangling pointer read or write (use-after-free) a memory location that is outside the
GitHub
github.com › NVombat › Use-After-Free
GitHub - NVombat/Use-After-Free: CWE-416 Use-After-Free Vulnerability, Attack and Fix · GitHub
Free the chunks of memory using option 3. Select option 2 to allocate a chunk of memory for the password so that it can rewrite the contents of the previously allocated username chunk too. Use option 4 to log in and successfully exploit the vulnerability
Author NVombat
Fortect
fortect.com › how to › how to detect and fix the “use after free” (uaf) bug on windows
How to Detect and Fix "Use After Free" (UAF) bug on Windows
May 25, 2025 - Understanding and mitigating UAF vulnerabilities is crucial for maintaining the security and stability of your system. Use After Free (UAF) refers to a class of bugs where a program continues to access memory after it has been freed. This happens ...