An issue was discovered in Oniguruma 6.x before 6.9.4rc2. In the function fetchintervalquantifier (formerly known as fetchrange_quantifier) in regparse.c, PFETCH is called without checking PEND. This leads to a heap-based buffer over-read.
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2019-19204.json"