CVE-2024-45506Known exploitationNetwork attack vector

Remote process crash via stale HTTP/2 flags

Published Sep 4, 2024 · Updated Mar 14, 2025

Denial of service in affected HAProxy 2.9, 3.0, and 3.1 builds allows remote attackers to crash the proxy through HTTP/2 traffic. When h2_release_mbuf empties the mux output buffer after a GOAWAY, it leaves H2_CF_MUX_MFULL and H2_CF_DEM_MROOM set; h2_send then skips mux processing and loops forever. Reachability requires HTTP/2 zero-copy forwarding and a rare buffer-full error sequence; the watchdog terminates the stuck process, interrupting proxied service.

CVSS severity7.5
High
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected HAProxy 2.9, 3.0, and 3.1 builds allows remote attackers to crash the proxy through HTTP/2 traffic. When h2_release_mbuf empties the mux output buffer after a GOAWAY, it leaves H2_CF_MUX_MFULL and H2_CF_DEM_MROOM set; h2_send then skips mux processing and loops forever. Reachability requires HTTP/2 zero-copy forwarding and a rare buffer-full error sequence; the watchdog terminates the stuck process, interrupting proxied service.

The record

CVE
CVE-2024-45506
Published
Sep 4, 2024
Updated
Mar 14, 2025
Vendor
HAProxy Technologies
Product
HAProxy
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 4, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 14, 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=2.9.0 <2.9.10
  2. Affected versionversion=3.0.0 <3.0.4
  3. Affected versionversion=3.1.0 <3.1-dev6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

HAProxy Technologies · HAProxyversion=2.9.0 <2.9.10; version=3.0.0 <3.0.4; version=3.1.0 <3.1-dev6

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
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.

Reported exploitation

Technologies

Your stack

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Your stack

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