{"id":"CVE-2020-11767","url":"https://www.cyber-defence.io/tools/cve/CVE-2020-11767","generatedAt":"2026-10-27T22:26:28.762Z","title":"Istio through 1.5.1 and Envoy through 1.14.1 have a data-leak issue.","description":"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.","published":"2020-04-15T02:15:14.000Z","lastModified":"2026-06-17T02:50:46.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":3.1,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N"},"cwe":[],"affected":["envoyproxy/envoy","istio/istio"],"epss":{"score":0.01818,"percentile":0.78576,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (1.82%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://bugs.chromium.org/p/chromium/issues/detail?id=954160#c5","tags":["Issue Tracking","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/envoyproxy/envoy/issues/6767","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/istio/istio/issues/13589","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/istio/istio/issues/9429","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://bugs.chromium.org/p/chromium/issues/detail?id=954160#c5","tags":["Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/envoyproxy/envoy/issues/6767","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/istio/istio/issues/13589","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/istio/istio/issues/9429","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2020-11767","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}