CVE-2022-23606Network attack vector

Proxy crash via recursive idle-connection draining

Published Feb 22, 2022 · Updated Apr 23, 2025

Uncontrolled recursion in Envoy 1.20.0 through 1.20.1 and 1.21.0 allows remote authenticated users to crash the proxy via CDS. The ConnPoolImplBase connection-event path re-enters idle-connection draining while a deleting cluster closes each idle client, nesting callbacks until the process stack is exhausted. Exploitation requires control of CDS cluster deletion and a large idle pool; the resulting process termination interrupts proxy service.

CVSS severity4.4
Medium
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in Envoy 1.20.0 through 1.20.1 and 1.21.0 allows remote authenticated users to crash the proxy via CDS. The ConnPoolImplBase connection-event path re-enters idle-connection draining while a deleting cluster closes each idle client, nesting callbacks until the process stack is exhausted. Exploitation requires control of CDS cluster deletion and a large idle pool; the resulting process termination interrupts proxy service.

The record

CVE
CVE-2022-23606
Published
Feb 22, 2022
Updated
Apr 23, 2025
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-674, T1499.004
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Feb 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.20.0, < 1.20.2
  2. Affected versionversion=>= 1.21.0, < 1.21.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Envoy Proxy · Envoyversion=>= 1.20.0, < 1.20.2; version=>= 1.21.0, < 1.21.1

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.4GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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