CVE-2024-23326Network attack vector

Data disclosure via incorrect HTTP upgrade state

Published Jun 4, 2024 · Updated Aug 1, 2024

Request smuggling in Envoy before 1.30.2 allows remote attackers to read proxied data via crafted protocol-upgrade traffic. The source/common/router upgrade path enters raw TCP tunneling when an upstream server returns HTTP 200 with an Upgrade header instead of requiring status 101. Exploitation requires a tricked upstream server to add that response header during an upgrade request, enabling desynchronized traffic to disclose proxied data.

CVSS severity5.9
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Request smuggling in Envoy before 1.30.2 allows remote attackers to read proxied data via crafted protocol-upgrade traffic. The source/common/router upgrade path enters raw TCP tunneling when an upstream server returns HTTP 200 with an Upgrade header instead of requiring status 101. Exploitation requires a tricked upstream server to add that response header during an upgrade request, enabling desynchronized traffic to disclose proxied data.

The record

CVE
CVE-2024-23326
Published
Jun 4, 2024
Updated
Aug 1, 2024
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-391, CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 1, 2024Record 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=>= 1.13.0, <= 1.30.1
  2. Affected versionversion=<= 1.27.5
  3. Affected versionversion=>= 1.28.0, <= 1.28.3
  4. Affected versionversion=>= 1.29.0, <= 1.29.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=>= 1.13.0, <= 1.30.1; version=<= 1.27.5; version=>= 1.28.0, <= 1.28.3; version=>= 1.29.0, <= 1.29.4

Published CVSS scores

8.2NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
5.9GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-391Unchecked Error Condition
CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
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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