CVE-2019-19203

An out-of-bounds read vulnerability was found in the way Oniguruma handled regular expressions with GB18030 character encoding. A UChar pointer is dereferenced without checking if it passed the end of the matched string, leading to a heap-based buffer over-read. A remote attacker could abuse this flaw by providing a malformed regular expression that, when processed by an application linked to Oniguruma, might crash the application causing a denial of service.

This flaw did not affect the versions of Oniguruma (embedded in php) as shipped with Red Hat Enterprise Linux 5, as they did not include support for GB18030 character encoding, which was introduced in a later version of the library.

The versions of Ruby as shipped with Red Hat Enterprise Linux and Red Hat Software Collections 3 do not use Oniguruma but rather Onigmo, a regular expressions library forked from Oniguruma focusing on new expressions supported in Perl 5.10+. Those versions are affected by this flaw because both Onigmo and Oniguruma share the same vulnerable code. However, Ruby does perform additional checks which prevent the vulnerable code path to be easily reached, hence lowering the severity of the flaw.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.