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The Internet Systems Consortium's (ISC) Dynamic Host Configuration Protocol (DHCP) contained a vulnerability that introduced several potential buffer overflow conditions. ISC DHCP makes use of the {{vsnprintf()}} function for writing various log file strings, which is defined in in the Open Group Base Specifications Issue 6 \[[Open Group 04|AA. C References#Open Group 04]\] as well as C99 \[[ISO/IEC 9899-:1999|AA. C References#ISO/IEC 9899-1999]\]. For systems that do not support {{vsnprintf()}}, a C include file was created that defines the {{vsnprintf()}} function to {{vsprintf()}} as shown in this non-compliant code example:

\[[ISO/IEC 9899-:1999|AA. C References#ISO/IEC 9899-1999]\] Section 7.19.6.12, "The {{vsnprintf}} function"
\[[Open Group 04|AA. C References#Open Group 04]\] [{{vsnprintf()}}|http://www.opengroup.org/onlinepubs/009695399/functions/vsnprintf.html]
\[[Seacord 05|AA. C References#Seacord 05]\] Chapter 6, "Formatted Output"
\[[VU#654390|AA. C References#VU#654390]\]