Versions mentioned in the description apply to the upstream
Remediation section below for
Debian:9 relevant versions.
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_])?)+)+$/.
pcre3 to version 2:8.38-1 or higher.