The get_repeat_type function in basic_regex_creator.hpp in the Boost regex library (aka Boost.Regex) in Boost 1.33 and 1.34 allows context-dependent attackers to cause a denial of service (NULL dereference and crash) via an invalid regular expression.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.