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Fencer Vulns
medium 6.1

CVE-2021-43825 json

Use-after-free in Envoy

published 2022-02-22 4 y ago modified 2026-09-08 2 mo ago also BIT-envoy-2021-43825 , EUVD-2021-30705 , GHSA-h69p-g6xg-mhhh

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

Envoy is an open source edge and service proxy, designed for cloud-native applications. Sending a locally generated response must stop further processing of request or response data. Envoy tracks the amount of buffered request and response data and aborts the request if the amount of buffered data is over the limit by sending 413 or 500 responses. However when the buffer overflows while response is processed by the filter chain the operation may not be aborted correctly and result in accessing a freed memory block. If this happens Envoy will crash resulting in a denial of service.

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-2021-43825 updated cvss 7.5

envoy: Use-after-free when response filters increase response data

  • 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
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

0.88% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L
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 5.0 AV:N/AC:L/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.