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Weakness · High

CWE-415: Double Free

What it is

The product calls free() twice on the same memory address.

Likelihood of exploit: High4 exploited in the wildMITRE CWE 4.19.1

Severity (our rating)
High
Likelihood of exploit
High
Introduced during
Implementation
Exploited in the wild
4 known exploited CVEs

What an attacker can do

  • Modify Memory (Integrity, Confidentiality, Availability)
  • Execute Unauthorized Code or Commands (Integrity, Confidentiality, Availability)

How to prevent it

Architecture and Design

  • Choose a language that provides automatic memory management.

Implementation

  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

How to find it

  • Fuzzing. Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
  • Automated Static Analysis. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
  • Automated Dynamic Analysis. Use tools that are integrated during compilation to insert runtime error-checking mechanisms related to memory safety errors, such as AddressSanitizer (ASan) for C/C++.

CWE-415 on MITRE's CWE site

Exploited in the wild: 4 CVEs

Vulnerabilities caused by CWE-415 that attackers have used, from CISA's Known Exploited Vulnerabilities catalog, newest first.

All known exploited vulnerabilities

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Source: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.