CVE-2021-32781

What it is

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions after Envoy sends a locally generated response it must stop further processing of request or response data. However when local response is generated due the internal buffer overflow while request or response is processed by the filter chain the operation may not be stopped completely and result in accessing a freed memory block. A specifically constructed request delivered by an untrusted downstream or upstream peer in the presence of extensions that modify and increase the size of request or response bodies resulting in a Denial of Service when using extensions that modify and increase the size of request or response bodies, such as decompressor filter. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to address incomplete termination of request processing after locally generated response. As a workaround disable Envoy's decompressor, json-transcoder or grpc-web extensions or proprietary extensions that modify and increase the size of request or response bodies, if feasible.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

1.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-08-24 21:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:53 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.3% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-08-24 21:15 UTC

Last modified

2026-06-17 03:53 UTC

Exploit probability

1.3% · EPSS, next 30 days

Weakness

CWE-416 · Use after free

Record status

Modified

Affected

• Envoyproxy Envoy < 1.16.5
• Envoyproxy Envoy < 1.17.4
• Envoyproxy Envoy < 1.18.4
• Envoyproxy Envoy 1.19.0

Attack profile CVSS 3.1 · 8.6

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-32781.md and follow it. Check whether this project is affected by CVE-2021-32781. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge