CVE-2024-23324Network attack vector

Authentication bypass via unsanitized PROXY protocol TLVs

Published Feb 9, 2024 · Updated Aug 19, 2024

Authentication bypass in affected Envoy releases allows remote attackers to evade ext_authz checks via crafted PROXY protocol TLVs. The Proxy protocol listener filter inserts non-UTF-8 TLV bytes directly into protobuf string metadata, causing the ext_authz gRPC request to be invalid. Exploitation requires PROXY protocol TLV pass-through and failure_mode_allow=true; a downstream client then reaches protected resources without authorization.

CVSS severity8.6
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in affected Envoy releases allows remote attackers to evade ext_authz checks via crafted PROXY protocol TLVs. The Proxy protocol listener filter inserts non-UTF-8 TLV bytes directly into protobuf string metadata, causing the ext_authz gRPC request to be invalid. Exploitation requires PROXY protocol TLV pass-through and failure_mode_allow=true; a downstream client then reaches protected resources without authorization.

The record

CVE
CVE-2024-23324
Published
Feb 9, 2024
Updated
Aug 19, 2024
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2024Record 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=0 <1.26.7
  2. Affected versionversion=< 1.26.7
  3. Affected versionversion=>= 1.27.0, < 1.27.3
  4. Affected versionversion=1.27.0 <1.27.3
  5. Affected versionversion=>= 1.28.0, < 1.28.1
  6. Affected versionversion=1.28.0 <1.28.1
  7. Affected versionversion=>= 1.29.0, < 1.29.1
  8. Affected versionversion=1.29.0 <1.29.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=0 <1.26.7; version=< 1.26.7; version=>= 1.27.0, < 1.27.3; version=1.27.0 <1.27.3; version=>= 1.28.0, < 1.28.1; version=1.28.0 <1.28.1; version=>= 1.29.0, < 1.29.1; version=1.29.0 <1.29.1

Published CVSS scores

8.6GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

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-20Improper Input Validation
T1190Exploit Public-Facing Application

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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