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CVE-2021-43825

Use-after-free in Envoy

6.1 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
Low

Exploit likelihood

0.88%Unchanged since Feb 23, 2022
90%50%10%1%

What each source reports

CVE List Score used 6.1

Use-after-free in Envoy

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.

Record
CVE-2021-43825
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L
Weakness
CWE-416
Updated
2026-11-02
EUVDEUVD-2021-30705 6.1

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.

Record
EUVD-2021-30705
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L
Updated
2026-11-02
NVD 6.1

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.

Record
CVE-2021-43825
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-416
Updated
2026-11-02
OSV 7.5

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.

Record
CVE-2021-43825
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRHSA-2022:1275 9.4

Red Hat Security Advisory: Red Hat OpenShift Service Mesh 2.1.2 security update

Record
RHSA-2022:1275
CVSS 3.1
9.4 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Updated
2026-11-02
OSVRHSA-2022:1276 9.4

Red Hat Security Advisory: Red Hat OpenShift Service Mesh 2.0.9 security update

Record
RHSA-2022:1276
CVSS 3.1
9.4 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Updated
2026-11-02
OSVBIT-envoy-2021-43825 No score

Use-after-free in Envoy

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.

Record
BIT-envoy-2021-43825
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
envoy
Bitnami
 before 1.18.6, 1.19.0 up to 1.19.3, 1.20.0 up to 1.20.2, 1.21.0 up to 1.21.1
1.18.61.19.31.20.21.21.1
servicemesh-proxy
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh-proxy-debuginfo
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh-proxy-debugsource
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh-proxy-wasm
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh-cni
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh-pilot-agent
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh-pilot-discovery
Red Hat:service_mesh:2.1::el8
From an advisory covering 8 CVEs
 before 0:2.1.2-4.el8
0:2.1.2-4.el8
servicemesh
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8
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Affected packages
PackageAffectedFixed
servicemesh-istioctl
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8
servicemesh-mixc
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8
servicemesh-mixs
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8
servicemesh-pilot-agent
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8
servicemesh-pilot-discovery
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8
kiali
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:v1.24.7.redhat1-1.el8
0:v1.24.7.redhat1-1.el8
servicemesh-prometheus
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.14.0-16.el8.1
0:2.14.0-16.el8.1
servicemesh-proxy
Red Hat:service_mesh:2.0::el8
From an advisory covering 16 CVEs
 before 0:2.0.9-3.el8
0:2.0.9-3.el8

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-43825 is a medium vulnerability (CVSS 6.1) in Envoyproxy Envoy, published February 22, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.88%, the 59th percentile. Fixed in envoy 1.18.6.

References

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