Perl-Compatible Regular Expression (PCRE) library before 6.7 does not properly calculate the compiled memory allocation for regular expressions that involve a quantified "subpattern containing a named recursion or subroutine reference," which allows context-dependent attackers to cause a denial of service (error or crash).
Exploitability
AV:NAC:MAu:NImpact
C:NI:NA:P4.3/AV:N/AC:M/Au:N/C:N/I:N/A:P