CNCF Envoy through 1.13.0 TLS inspector bypass. TLS inspector could have been bypassed (not recognized as a TLS client) by a client using only TLS 1.3. Because TLS extensions (SNI, ALPN) were not inspected, those connections might have been matched to a wrong filter chain, possibly bypassing some security restrictions in the process.
https://www.envoyproxy.io/docs/envoy/v1.13.1/intro/version_history
https://github.com/envoyproxy/envoy/security/advisories/GHSA-c4g8-7grc-5wvx