{% extends "introduction/base.html" %} 
{% load static %} 
{% block content %} 
{% block title %}
<title>Use after free</title>
{% endblock %}
<div class="container">
  <h2 style="font-size: 2.7rem">CWE-416: <span>User after free</span></h2>
</div>
<div class="box">
  Referencing memory after it has been freed can cause a program to crash, use
  unexpected values, or execute code.
  <br />
  <ul>
    <li>Error conditions and other exceptional circumstances.</li>
    <li>
      Confusion over which part of the program is responsible for freeing the
      memory.
    </li>
  </ul>
  In this case, after the memory has been released, it is lawfully assigned to a
  different pointer. The initial pointer to the memory that was freed is
  utilised once more and now points to a position within the new allocation. As
  the data is modified, it corrupts the memory that is still being used, leading
  to unpredictable behaviour. Several function pointers might be dispersed
  throughout the heap data in C++, for example, if the freshly allocated data
  has a potential to contain a class. The execution of arbitrary code is
  possible if one of these function pointers is overwritten with an address to
  legitimate shellcode.
  <br>
  <br>
  To prevent Use After Free vulnerabilities, software developers should carefully 
  manage memory allocation and deallocation, validate user input to ensure that it 
  does not trigger a double-free condition, and use safe programming practices that 
  automatically detect and prevent the use of freed memory. Tools like memory-safe 
  programming languages and memory-management libraries can also help prevent this 
  type of vulnerability.
</div>
{% endblock %}