CVE-2024-53008Network attack vector

ACL bypass via malformed HTTP/3 headers

Published Nov 28, 2024 · Updated Nov 29, 2024

HTTP request smuggling in HAProxy allows remote attackers to read ACL-restricted data through malformed HTTP/3 headers. The HTTP/3 parser accepts malformed pseudo-header fields, including incompletely validated :method and :scheme values, and forwards them to a noncompliant HTTP/1.1 back end that parses the request differently. Exploitation requires an HTTP/3 frontend, a noncompliant HTTP/1.1 backend, and an ACL-protected path; the bounded consequence is disclosure of data behind that ACL.

CVSS severity5.3
Medium
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

HTTP request smuggling in HAProxy allows remote attackers to read ACL-restricted data through malformed HTTP/3 headers. The HTTP/3 parser accepts malformed pseudo-header fields, including incompletely validated :method and :scheme values, and forwards them to a noncompliant HTTP/1.1 back end that parses the request differently. Exploitation requires an HTTP/3 frontend, a noncompliant HTTP/1.1 backend, and an ACL-protected path; the bounded consequence is disclosure of data behind that ACL.

The record

CVE
CVE-2024-53008
Published
Nov 28, 2024
Updated
Nov 29, 2024
Vendor
HAProxy Technologies
Product
HAProxy
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 28, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 29, 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=2.6.18 and earlier
  2. Affected versionversion=2.6 <=2.6.18
  3. Affected versionversion=2.8.10 and earlier
  4. Affected versionversion=2.8 <=2.8.10
  5. Affected versionversion=2.9 <=2.9.9
  6. Affected versionversion=2.9.9 and earlier
  7. Affected versionversion=3.0.2 and earlier
  8. Affected versionversion=3.0 <=3.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

HAProxy Technologies · HAProxyversion=2.6.18 and earlier; version=2.6 <=2.6.18; version=2.8.10 and earlier; version=2.8 <=2.8.10; version=2.9 <=2.9.9; version=2.9.9 and earlier; version=3.0.2 and earlier; version=3.0 <=3.0.2

Published CVSS scores

5.3JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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-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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo