Use of Prohibited Code

The product uses a function, library, or third party component that has been explicitly prohibited, whether by the developer or the customer.


The developer - or customers - may wish to restrict or eliminate use of a function, library, or third party component for any number of reasons, including real or suspected vulnerabilities; difficulty to use securely; export controls or license requirements; obsolete or poorly-maintained code; internal code being scheduled for deprecation; etc.

To reduce risk of vulnerabilities, the developer might maintain a list of "banned" functions that programmers must avoid using because the functions are difficult or impossible to use securely. This issue can also make the product more costly and difficult to maintain.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

The code below calls the gets() function to read in data from the command line.

char buf[24];
  printf("Please enter your name and press <Enter>\n");

However, gets() is inherently unsafe, because it copies all input from STDIN to the buffer without checking size. This allows the user to provide a string that is larger than the buffer size, resulting in an overflow condition.

Example Two

The following code attempts to create a local copy of a buffer to perform some manipulations to the data.

void manipulate_string(char * string){
  char buf[24];
  strcpy(buf, string);

However, the programmer does not ensure that the size of the data pointed to by string will fit in the local buffer and copies the data with the potentially dangerous strcpy() function. This may result in a buffer overflow condition if an attacker can influence the contents of the string parameter.

See Also

Comprehensive Categorization: Poor Coding Practices

Weaknesses in this category are related to poor coding practices.

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Quality Weaknesses with Indirect Security Impacts

CWE identifiers in this view (slice) are quality issues that only indirectly make it easier to introduce a vulnerability and/or make the vulnerability more difficult t...

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

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