PCRE 7.8 and 8.32 through 8.37, and PCRE2 10.10 mishandle group empty matches, which might allow remote attackers to cause a denial of service (stack-based buffer overflow) via a crafted regular expression, as demonstrated by /^(?:(?(1)\\.|([^\\\\W_])?)+)+$/.

Heap-based buffer overflow in the find_fixedlength function in pcre_compile.c in PCRE before 8.38 allows remote attackers to cause a denial of service (crash) or obtain sensitive information from heap memory and possibly bypass the ASLR protection mechanism via a crafted regular expression with an excess closing parenthesis.

The pcre_compile function in pcre_compile.c in PCRE before 8.38 mishandles certain [: nesting, which allows remote attackers to cause a denial of service (CPU consumption) or possibly have unspecified other impact via a crafted regular expression, as demonstrated by a JavaScript RegExp object encountered by Konqueror.