CVE-2024-23327Network attack vector

Unauthenticated proxy crash via addressless PPv2 header

Published Feb 9, 2024 · Updated Jun 9, 2025

NULL pointer dereference in affected Envoy releases allows remote attackers to crash the proxy through a crafted PPv2 LOCAL header. The listener accepts a LOCAL command without address data, leaves proxy-protocol filter-state source and destination addresses null, and upstream generateV2Header dereferences them. Exploitation requires PROXY protocol v2 on both the downstream listener and upstream cluster; a matching unauthenticated connection terminates Envoy.

CVSS severity7.5
High
EPSS probability0.69%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in affected Envoy releases allows remote attackers to crash the proxy through a crafted PPv2 LOCAL header. The listener accepts a LOCAL command without address data, leaves proxy-protocol filter-state source and destination addresses null, and upstream generateV2Header dereferences them. Exploitation requires PROXY protocol v2 on both the downstream listener and upstream cluster; a matching unauthenticated connection terminates Envoy.

The record

CVE
CVE-2024-23327
Published
Feb 9, 2024
Updated
Jun 9, 2025
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-476, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 1.26.7
  2. Affected versionversion=>= 1.27.0, < 1.27.3
  3. Affected versionversion=>= 1.28.0, < 1.28.1
  4. Affected versionversion=>= 1.29.0, < 1.29.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=< 1.26.7; version=>= 1.27.0, < 1.27.3; version=>= 1.28.0, < 1.28.1; version=>= 1.29.0, < 1.29.1

Published CVSS scores

7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

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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