Out-of-bounds write in Oniguruma - CVE-2017-9225

Detailed vulnerability description

The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.

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.

How to mitigate CVE-2017-9225

Sources

• https://github.com/kkos/oniguruma/commit/166a6c3999bf06b4de0ab4ce6b088a468cc4029f
• https://github.com/kkos/oniguruma/issues/56