CVE-2006-20001Network attack vector

Worker crash via invalid Not prefix parsing

Published Jan 17, 2023 · Updated Feb 13, 2025

Out-of-bounds access in mod_dav in Apache HTTP Server 2.4.54 and earlier allows remote attackers to crash a worker via a crafted If header. The dav_process_if_header parser advances its list pointer by two bytes after an invalid Not prefix instead of rejecting the token, permitting access beyond the header buffer. The path is reachable where mod_dav processes requests for a DAV-enabled location, and the bounded reported consequence is a worker-process crash.

CVSS severity7.5
High
EPSS probability3.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds access in mod_dav in Apache HTTP Server 2.4.54 and earlier allows remote attackers to crash a worker via a crafted If header. The dav_process_if_header parser advances its list pointer by two bytes after an invalid Not prefix instead of rejecting the token, permitting access beyond the header buffer. The path is reachable where mod_dav processes requests for a DAV-enabled location, and the bounded reported consequence is a worker-process crash.

The record

CVE
CVE-2006-20001
Published
Jan 17, 2023
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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=2.4 <=2.4.54

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=2.4 <=2.4.54

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.3IBMCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-787Out-of-bounds Write
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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