Adobe Flash Player versions 220.127.116.11 and earlier, 18.104.22.1684 and earlier have an exploitable buffer overflow / underflow vulnerability in the RegExp class related to backtrack search functionality. Successful exploitation could lead to arbitrary code execution.
CWE-787 - Out-of-Bounds Write
Out-of-bounds write vulnerability is a memory access bug that allows software to write data past the end or before the beginning of the intended buffer. This may result in the corruption of data, a crash, or arbitrary code execution.