Integer overflow in the regcomp implementation in the Henry Spencer BSD regex library (aka rxspencer) alpha3.8.g5 on 32-bit platforms, as used in NetBSD through 6.1.5 and other products, might allow context-dependent attackers to execute arbitrary code via a large regular expression that leads to a heap-based buffer overflow.
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.