CWE - 416 : Use After Free
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CWE Definition
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http://cwe.mitre.org/data/definitions/416.html
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Number of vulnerabilities:
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901
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Description
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Referencing memory after it has been freed can cause a program
to crash, use unexpected values, or execute code. |
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Background Details
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Other Notes
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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.
The simplest way data corruption may occur involves the system's reuse of
the freed memory. Like double free errors and memory leaks, use after free
errors have two common and sometimes overlapping causes: - Error conditions
and other exceptional circumstances. - Confusion over which part of the
program is responsible for freeing the memory. In this scenario, the memory
in question is allocated to another pointer validly at some point after it
has been freed. The original pointer to the freed memory is used again and
points to somewhere within the new allocation. As the data is changed, it
corrupts the validly used memory; this induces undefined behavior in the
process. If the newly allocated data chances to hold a class, in C++ for
example, various function pointers may be scattered within the heap data. If
one of these function pointers is overwritten with an address to valid
shellcode, execution of arbitrary code can be achieved. |
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Warning! CWE definitions are provided as a quick reference. They are
not complete and may not be up to date!
You must visit
http://cwe.mitre.org/ for a complete list of CWE entries
and for more details.
