{"id":"CVE-2020-11767","aliases":["BIT-envoy-2020-11767","EUVD-2020-4109","GHSA-hvwr-mw2m-chj3"],"status":"published","title":"Istio through 1.5.1 and Envoy through 1.14.1 have a data-leak issue. If there is a TCP connection...","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.","severity":{"version":"3.1","score":3.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N","level":"low","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.01818,"percentile":0.78903,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-200"],"published":"2020-04-15T01:05:38Z","modified":"2026-10-20T10:51:03Z","fixes":[{"ecosystem":"Bitnami","package":"envoy","fixed_in":["1.14.2"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Bitnami","package":"envoy","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.14.2"}]}]}],"products":[{"vendor":"envoyproxy","product":"envoy"},{"vendor":"istio","product":"istio"}],"references":[{"url":"https://bugs.chromium.org/p/chromium/issues/detail?id=954160#c5","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","advisory","report"]},{"url":"https://github.com/envoyproxy/envoy/issues/6767","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","advisory"]},{"url":"https://github.com/istio/istio/issues/9429","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","advisory"]},{"url":"https://github.com/istio/istio/issues/13589","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","advisory","evidence"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-11767","tags":["web"]},{"url":"https://github.com/advisories/GHSA-hvwr-mw2m-chj3"}],"sources":{"cve":[{"id":"CVE-2020-11767","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.","status":"published","published":"2020-04-15T01:05:38Z","modified":"2024-08-04T11:41:59.75Z","updated_at":"2026-11-02T14:35:57.352161Z"}],"euvd":[{"id":"EUVD-2020-4109","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.","status":"published","published":"2020-04-15T01:05:38Z","modified":"2024-08-04T11:41:59Z","updated_at":"2026-11-03T03:07:42.412087Z"}],"ghsa":[{"id":"GHSA-hvwr-mw2m-chj3","title":"Istio through 1.5.1 and Envoy through 1.14.1 have a data-leak issue. If there is a TCP connection...","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.","status":"published","published":"2022-05-24T17:14:43Z","modified":"2023-01-29T05:02:17Z","cwes":["CWE-200"],"updated_at":"2026-11-02T14:45:02.517815Z"}],"nvd":[{"id":"CVE-2020-11767","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.","status":"published","published":"2020-04-15T02:15:14Z","modified":"2026-06-17T02:50:45.547Z","cvss":[{"version":"3.1","score":3.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N","level":"low","assessor":"primary"},{"version":"2.0","score":2.6,"vector":"AV:N/AC:H/Au:N/C:P/I:N/A:N","level":"low","assessor":"primary"}],"updated_at":"2026-11-02T14:05:57.678762Z"}],"osv":[{"id":"CVE-2020-11767","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.","status":"published","published":"2020-04-15T02:15:14Z","modified":"2026-10-20T10:51:03.981106329Z","cvss":[{"version":"3.1","score":3.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N","level":"low"}],"updated_at":"2026-11-02T15:44:14.034736Z"},{"id":"BIT-envoy-2020-11767","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.","status":"published","published":"2024-03-06T11:01:15.092Z","modified":"2026-09-08T08:47:08.112856068Z","updated_at":"2026-11-02T15:28:29.563843Z"}]}}