Istio before 1.1.13 and 1.2.x before 1.2.4 mishandles regular expressions for long URIs, leading to a denial of service during use of the JWT, VirtualService, HTTPAPISpecBinding, or QuotaSpecBinding API.
https://istio.io/blog/2019/istio-security-003-004/
https://github.com/envoyproxy/envoy/issues/7728
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86164
https://discuss.istio.io/t/upcoming-security-updates-in-istio-1-2-4-and-1-1-13/3383