CVE-2020-11767

lowpriority · track · 13EPSS 0.018 · 79 %ileEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.82% (79th) EPSS
CVSS 2.6 · low
Is it mine?
4 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-27

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

3.1
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.02.6lowAV:N/AC:H/Au:N/C:P/I:N/A:Nprimary · NVD / NIST USexploitability 4.9 · impact 2.9
v3.13.1lowCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:Nprimary · NVD / NIST USexploitability 1.6 · impact 1.4
v3.12.9lowCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-200USLLM-inferred
03

affected products (4)

Products and version ranges known to be affected.

04

advisories (1)

Vendor and ecosystem advisories describing this.

  • BIT-envoy-2020-117672024-03-06vendor · osvUS

    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.

05

also known as (3)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdnvdosvNVDCVE.orgMITRE
published 2020-04-15modified 2026-06-17
07

references (14)

External citations — patches, advisories, analysis.

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