CVE-2020-11767

LOW
3.1
CVSS Score
Published: April 15, 2020 at 01:05 AM UTC
Updated: June 17, 2026 at 02:50 AM UTC
2 products affected across 2 vendorsEnvoyIstio

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Severity
LOW3.1
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 1.14.1
v ≤ 1.5.1

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (4)

x_refsource_MISCIssue TrackingThird Party Advisory
https://bugs.chromium.org/p/chromium/issues/detail?id=954160#c5
x_refsource_MISCThird Party Advisory
https://github.com/envoyproxy/envoy/issues/6767
x_refsource_MISCExploitThird Party Advisory
https://github.com/istio/istio/issues/13589
x_refsource_MISCThird Party Advisory
https://github.com/istio/istio/issues/9429

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfo

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