CVE-2017-9225

An issue was discovered in Oniguruma 6.2.0, as used in Oniguruma-mod in
Ruby through 2.4.1 and mbstring in PHP through 7.1.5. A stack out-of-bounds
write in onigenc_unicode_get_case_fold_codes_by_str() occurs during regular
expression compilation. Code point 0xFFFFFFFF is not properly handled in
unicode_unfold_key(). A malformed regular expression could result in 4
bytes being written off the end of a stack buffer of
expand_case_fold_string() during the call to
onigenc_unicode_get_case_fold_codes_by_str(), a typical stack buffer
overflow.

Bugs

• <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=863313&gt;
• <https://github.com/kkos/oniguruma/issues/56&gt;