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Fencer Vulns
high 7.5

CVE-2021-43826 json

Crash when tunneling TCP over HTTP in Envoy

published 2022-02-22 4 y ago modified 2026-09-08 2 mo ago also BIT-envoy-2021-43826 , EUVD-2021-30706 , GHSA-cmx3-fvgf-83mf

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits
0
none known

Summary

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling <envoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config>` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade.

Patch / fix

  • bitnami envoy 1.18.6, 1.19.3, 1.20.2, 1.21.1
  • envoyproxy envoy 1.18.6, 1.19.3, 1.20.2, 1.21.1
  • kiali service mesh 2.0 v1.24.7.redhat1-1.el8
  • servicemesh service mesh 2.0 2.0.9-3.el8
  • servicemesh-mixc service mesh 2.0 2.0.9-3.el8
  • servicemesh-mixs service mesh 2.0 2.0.9-3.el8
  • servicemesh-proxy service mesh 2.0 2.0.9-3.el8
  • servicemesh-istioctl service mesh 2.0 2.0.9-3.el8
  • servicemesh-prometheus service mesh 2.0 2.14.0-16.el8.1
  • servicemesh-pilot-agent service mesh 2.0 2.0.9-3.el8

red hat advisories RHSA-2022:1276RHSA-2022:1275

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-43826 updated cvss 7.5

envoy: Use-after-free when tunneling TCP over HTTP

  • Red Hat OpenShift Service Mesh 2.0 servicemesh-proxy 2.0.9-3.el8
    fixed: vendor fix RHSA-2022:1276
  • Red Hat OpenShift Service Mesh 2.1 servicemesh-proxy 2.1.2-4.el8, servicemesh-proxy-wasm 2.1.2-4.el8
    fixed: vendor fix RHSA-2022:1275
  • Red Hat OpenShift Service Mesh 2.0 servicemesh 2.0.9-3.el8, kiali v1.24.7.redhat1-1.el8, servicemesh-cni 2.0.9-3.el8, servicemesh-mixc 2.0.9-3.el8, servicemesh-mixs 2.0.9-3.el8, servicemesh-istioctl 2.0.9-3.el8, +4 more Red Hat OpenShift Service Mesh 2.1 servicemesh 2.1.2-4.el8, servicemesh-cni 2.1.2-4.el8, servicemesh-operator 2.1.2-4.el8, servicemesh-ratelimit 2.1.2-4.el8, servicemesh-pilot-agent 2.1.2-4.el8, servicemesh-prometheus 2.23.0-5.el8, +1 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

1.06% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami envoy
<1.18.6
>=1.19.0, <1.19.3
>=1.20.0, <1.20.2
>=1.21.0, <1.21.1
1.18.6
1.19.3
1.20.2
1.21.1

Affected products

  • envoyproxy envoy

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.