{"id":"CVE-2020-11767","details":"Istio through 1.5.1 and Envoy through 1.14.1 have a data-leak issue. If there is a TCP connection (negotiated with SNI over HTTPS) to *.example.com, a request for a domain concurrently configured explicitly (e.g., abc.example.com) is sent to the server(s) listening behind *.example.com. The outcome should instead be 421 Misdirected Request. Imagine a shared caching forward proxy re-using an HTTP/2 connection for a large subnet with many users. If a victim is interacting with abc.example.com, and a server (for abc.example.com) recycles the TCP connection to the forward proxy, the victim's browser may suddenly start sending sensitive data to a *.example.com server. This occurs because the forward proxy between the victim and the origin server reuses connections (which obeys the specification), but neither Istio nor Envoy corrects this by sending a 421 error. Similarly, this behavior voids the security model browsers have put in place between domains.","aliases":["BIT-envoy-2020-11767"],"modified":"2026-08-07T15:11:34.354839Z","published":"2020-04-15T02:15:14Z","references":[{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/issues/6767"},{"type":"ADVISORY","url":"https://github.com/istio/istio/issues/9429"},{"type":"REPORT","url":"https://bugs.chromium.org/p/chromium/issues/detail?id=954160#c5"},{"type":"EVIDENCE","url":"https://github.com/istio/istio/issues/13589"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/envoyproxy/envoy","events":[{"introduced":"0"},{"last_affected":"3504d40f752eb5c20bc2883053547717bcb92fd8"}],"database_specific":{"cpe":"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"last_affected":"1.14.1"}],"source":"CPE_RANGE"}}],"versions":["v1.14.1","v1.14.0","v1.13.0","v1.12.0","v1.11.0","v1.10.0","v1.9.0","v1.8.0","v1.7.0","v1.6.0","v1.5.0","v1.4.0","v1.3.0","v1.2.0","v1.1.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-11767.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/istio/istio","events":[{"introduced":"0"},{"last_affected":"9d07e185b0dd50e6fb1418caa4b4d879788807e3"}],"database_specific":{"cpe":"cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"last_affected":"1.5.1"}],"source":"CPE_RANGE"}}],"versions":["1.5.1","1.5.0","1.5.0-beta.5","1.5.0-beta.4","1.5.0-beta.3","1.5.0-alpha.0","1.2.0-rc.3","1.2.0-rc.0","1.1.0-snapshot.2","1.1.0.snapshot.1","1.1.0.snapshot.0","1.0.0-snapshot.0","0.6.0","0.5.0","0.3.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-11767.json"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N"}]}