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Full vulnerability report · 2023
CVE-2006-20001High confidence

Apache HTTP Server: mod_dav out of bounds read, or write of zero byte

Apache Software Foundation · Apache HTTP Server

Official source article: Siemens SSA-806742 ↗. Check the applicable product and release in the original source.

7.5HighCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 11 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 3.55% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Apache Software Foundation Apache HTTP Server and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 11 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

4 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.55-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.55-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.55-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourceapache2Vendor fix publishedDebian records a fixed source-package version for this release.2.4.55-1Debian Security Tracker ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current · 1 archived
SSA-806742 · CSAF 2.0 · revision 1 · interimSiemens ProductCERTSSA-806742: Multiple Vulnerabilities in SCALANCE XCM-/XRM-300 before V2.4
11 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • SCALANCE XCH328 (6GK5328-4TS01-2EC2)
  • SCALANCE XCM324 (6GK5324-8TS01-2AC2)
  • SCALANCE XCM328 (6GK5328-4TS01-2AC2)
  • SCALANCE XCM332 (6GK5332-0GA01-2AC2)
  • SCALANCE XRH334 (24 V DC, 8xFO, CC) (6GK5334-2TS01-2ER3)
  • SCALANCE XRM334 (230 V AC, 12xFO) (6GK5334-3TS01-3AR3)
  • SCALANCE XRM334 (230 V AC, 8xFO) (6GK5334-2TS01-3AR3)
  • SCALANCE XRM334 (24 V DC, 12xFO) (6GK5334-3TS01-2AR3)
  • SCALANCE XRM334 (24 V DC, 8xFO) (6GK5334-2TS01-2AR3)
  • SCALANCE XRM334 (2x230 V AC, 12xFO) (6GK5334-3TS01-4AR3)
  • SCALANCE XRM334 (2x230 V AC, 8xFO) (6GK5334-2TS01-4AR3)
Summary
A carefully crafted If: request header can cause a memory read, or write of a single zero byte, in a pool (heap) memory location beyond the header value sent. This could cause the process to crash. This issue affects Apache HTTP Server 2.4.54 and earlier.
Remediation
Update to V2.4 or later version
CVE-2006-20001 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityhttpd: mod_dav: out-of-bounds read/write of zero byteNo longer in the provider’s current catalogue
26 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • httpd as a component of Red Hat Enterprise Linux 6
  • httpd-devel as a component of Red Hat Enterprise Linux 6
  • httpd-manual as a component of Red Hat Enterprise Linux 6
  • httpd-tools as a component of Red Hat Enterprise Linux 6
  • httpd.src as a component of Red Hat Enterprise Linux 6
  • mod_ssl as a component of Red Hat Enterprise Linux 6
  • httpd as a component of Red Hat Enterprise Linux 7
  • httpd-devel as a component of Red Hat Enterprise Linux 7
  • httpd-manual as a component of Red Hat Enterprise Linux 7
  • httpd-tools as a component of Red Hat Enterprise Linux 7
  • httpd.src as a component of Red Hat Enterprise Linux 7
  • mod_ldap as a component of Red Hat Enterprise Linux 7
Summary
A flaw was found in the mod_dav module of httpd. A specially crafted "If:" request header can cause a memory read or write of a single zero byte due to a missing error check, resulting in a Denial of Service.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Applications using the APR libraries, such as httpd, must be restarted for this update to take effect. After installing the updated packages, the httpd daemon will be restarted automatically.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2006-2000

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 11 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

A carefully crafted If: request header can cause a memory read, or write of a single zero byte, in a pool (heap) memory location beyond the header value sent. This could cause the process to crash. This issue affects Apache HTTP Server 2.4.54 and earlier.

What

A carefully crafted If: request header can cause a memory read, or write of a single zero byte, in a pool (heap) memory location beyond the header value sent. This could cause the process to crash. This issue affects Apache HTTP Server 2.4.54 and earlier.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

A carefully crafted If: request header can cause a memory read, or write of a single zero byte, in a pool (heap) memory location beyond the header value sent. This could cause the process to crash. This issue affects Apache HTTP Server 2.4.54 and earlier.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Out-of-bounds Write → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-787 ↗

CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-787
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2023-1424Xerox FreeFlow Print Server für Solaris: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Xerox FreeFlow Print Server ausnutzen, um die Vertraulichkeit, Verfügbarkeit und Integrität des Systems zu gefährden.

Official advisory ↗
BSI · German · WID-SEC-2023-0561Xerox FreeFlow Print Server: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Xerox FreeFlow Print Server ausnutzen, um die Vertraulichkeit, Verfügbarkeit und Integrität des Systems zu gefährden.

Official advisory ↗
BSI · German · WID-SEC-2024-1591Juniper JUNOS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Juniper JUNOS ausnutzen, um einen Denial of Service zu verursachen, Informationen offenzulegen, Privilegien zu erweitern und Sicherheitsmechanismen inklusive zu umgehen.

Official advisory ↗
BSI · German · WID-SEC-2023-0110Apache HTTP Server: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Apache HTTP Server ausnutzen, um einen Denial of Service Angriff durchzuführen und Sicherheitsmaßnahmen zu umgehen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20230118Security Bulletin 18 Jan 2023

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 18 Jan 2023, published on 18 January 2023. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0575Multiples vulnérabilités dans les produits Juniper Networks

t-a-device-CVE-2024-39565 Bulletin de sécurité Juniper Networks JSA83026 du 10 juillet 2024 https://supportportal.juniper.net/s/article/2024-07-Security-Bulletin-Junos-Space-Multiple-vulnerabilities-resolved-in-24-1R1-release Bulletin de sécurité Juniper Networks JSA83027 du 10 juillet 2024 https://supportportal.juniper.net/s/article/2024-07-Security-Bulletin-Session-Smart-Router-Multiple-vulnerabilities-resolved Bulletin de sécurité Juniper Networks JSA75726 du 11 juillet 2024 https://supportportal.juniper.net/s/article/2024-07-Security-Bulletin-Junos-OS-and-Junos-OS-Evolved-Malformed-BGP-UPDATE-causes-RPD-crash-CVE-2024-39552 Référence CVE CVE-2006-20001 https://www.cve.org/CVERecord?id=CVE-2006-20001 Référence CVE CVE-2011-1473 https://www.cve.org/CVERecord?id=CVE-2011-1473 Référence CVE CVE-2011-5094 https://www.cve.org/CVERecord?id=CVE-2011-5094 Référence CVE CVE-2014-10064 https://www.cve.org/CVERecord?id=CVE-2014-10064 Référence CVE CVE-2014-7191 https://www.cve.org/CVERecord?id=CVE-2014-7191 Référence CVE CVE-2015-9262 https://www.cve.org/CVERecord?id=CVE-2015-9262 Référence CVE CVE-2016-1000232 https://www.cve.org/CVERecord?id=CVE-2016-1000232 Référence CVE CVE-2016-10540 https://www.cve.org/CVERecord?id=CVE-2016-10540 Référence CVE CVE-2016-4658 https://www.cve.org/CVERecord?id=CVE-2

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0119Multiples vulnérabilités dans les produits Siemens

ssa-716164.html Bulletin de sécurité Siemens SSA-753746 du 13 février 2024 https://cert-portal.siemens.com/productcert/html/ssa-753746.html Bulletin de sécurité Siemens SSA-797296 du 13 février 2024 https://cert-portal.siemens.com/productcert/html/ssa-797296.html Bulletin de sécurité Siemens SSA-806742 du 13 février 2024 https://cert-portal.siemens.com/productcert/html/ssa-806742.html Bulletin de sécurité Siemens SSA-871717 du 13 février 2024 https://cert-portal.siemens.com/productcert/html/ssa-871717.html Bulletin de sécurité Siemens SSA-943925 du 13 février 2024 https://cert-portal.siemens.com/productcert/html/ssa-943925.html Référence CVE CVE-2006-20001 https://www.cve.org/CVERecord?id=CVE-2006-20001 Référence CVE CVE-2019-19135 https://www.cve.org/CVERecord?id=CVE-2019-19135 Référence CVE CVE-2020-10735 https://www.cve.org/CVERecord?id=CVE-2020-10735 Référence CVE CVE-2020-11896 https://www.cve.org/CVERecord?id=CVE-2020-11896 Référence CVE CVE-2020-1967 https://www.cve.org/CVERecord?id=CVE-2020-1967 Référence CVE CVE-2020-1971 https://www.cve.org/CVERecord?id=CVE-2020-1971 Référence CVE CVE-2021-3445 https://www.cve.org/CVERecord?id=CVE-2021-3445 Référence CVE CVE-2021-36369 https://www.cve.org/CVERecord?id=CVE-2021-36369 Référence CVE CVE-2021-3638 https://www.cve.org/CVERecord?id=CVE-202

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0771Multiples vulnérabilités dans les produits Qnap

De multiples vulnérabilités ont été découvertes dans les produits Qnap . Elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance et un problème de sécurité non spécifié par l'éditeur.

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0188Multiples vulnérabilités dans les produits IBM

De multiples vulnérabilités ont été découvertes dans les produits IBM. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et un contournement de la politique de sécurité.

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0035Multiples vulnérabilités dans Apache HTTP Server

De multiples vulnérabilités ont été découvertes dans Apache HTTP Server. Elles permettent à un attaquant de provoquer un contournement de la politique de sécurité, une atteinte à l'intégrité des données et une atteinte à la confidentialité des données.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Applications using the APR libraries, such as httpd, must be restarted for this update to take effect. After installing the updated packages, the httpd daemon will be restarted automatically.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 17 Jan 2023 · Last source change 13 Feb 2025, 16:27 UTC · CWE-787 · Out-of-bounds Write

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2006-2000
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2006-20001 to advisory no longer present in the provider's current catalogue.
    Before
    remediation: access.redhat.com/CVE-2006-20001
    After
    advisory no longer present in the provider's current catalogue
    Red Hat Product Security ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    2.4 ≤ 2.4.54 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    2.4 ≤ 2.4.54 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Applications using the APR libraries, such as httpd, must be restarted for this update to take effect. After installing the updated packages, the httpd daemon will be restarted automatically.
    Red Hat Product Security ↗
  3. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Red Hat Product Security ↗
  4. Remediation statusRemediation status changed from Patch available to Mitigation available.
    Before
    Patch available
    After
    Mitigation available
    Siemens ProductCERT ↗
  5. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Remediation guidance recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2006-2000↗Siemens ProductCERT security advisory · Siemens SSA-806742↗Red Hat Product Security security advisory↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2006-20001 · cve.blacktree.nl