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Formatted input functions such as scanf(), fscanf(), vscanf(), and vfscanf() can be used to read string data from stdin or (in the cases of fscanf() and vfscanf()) other input stream. These functions work fine for valid integer values but lack robust error handling for invalid values.

Instead of these functions, try inputing the value as a string and then converting it to an integer value using {{strtol()}} or a related function \[[INT06-A|INT06-A. Use strtol() to convert a string token to an integer]\].

Risk Assessment

While it is relativley rare for a violation of this rule to result in a security vulnerability, it could more easily result in loss or misinterpreted data.

References

\[[Klein 02|AA. C References#Klein 02]]
\[[ISO/IEC 9899-1999|AA. C References#ISO/IEC 9899-1999]] Section 7.20.1.4, "The strtol, strtoll, strtoul, and strtoull functions," and Section 7.19.6, "Formatted input/output functions"