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Full vulnerability report · 2026
CVE-2026-109163High confidence

Apache HTTP Server: mod_vhost_alias 1 byte stack buffer overwrite (after CVE-2026-63292)

Apache Software Foundation · Apache HTTP Server

…UnscoredAssess manually
Recommended action
Needs assessment

No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityUnscoredOperational priority:Needs assessment, manual assessment needed.unscored

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.25% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • 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: Manual assessmentRemediation target: Manual assessment

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.

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
CVE-2026-109163 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityhttpd: httpd: Denial of Service via stack-based buffer overflow in mod_vhost_alias
34 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • httpd-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images
  • httpd-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images
  • httpd-0:2.4.71-0.1.hum1@src as a component of Red Hat Hardened Images
  • httpd-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images
  • httpd-core-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images
  • httpd-core-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images
  • httpd-core-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images
  • httpd-devel-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images
  • httpd-devel-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images
  • httpd-devel-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images
  • httpd-filesystem-0:2.4.71-0.1.hum1@noarch@public-hummingbird-aarch64-rpms as a component of Red Hat Hardened Images
  • httpd-filesystem-0:2.4.71-0.1.hum1@noarch@public-hummingbird-s390x-rpms as a component of Red Hat Hardened Images
Summary
A flaw was found in Apache HTTP Server's mod_vhost_alias module. A remote attacker could trigger a stack-based buffer overflow by sending a specially crafted HTTP request. This issue leads to a one-byte memory overwrite on the stack, which can crash the server process and result in a Denial of Service (DoS).
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
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.

Recommended actionNeeds assessment

No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.

Patch available
01

What, why and how

Stack-based buffer overflow vulnerability in Apache HTTP Server's mod_vhost_alias (after CVE-2026-63292) This issue affects Apache HTTP Server: 2.4.69.

What

Stack-based buffer overflow vulnerability in Apache HTTP Server's mod_vhost_alias (after CVE-2026-63292) This issue affects Apache HTTP Server: 2.4.69.

Why

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Stack-based buffer overflow vulnerability in Apache HTTP Server's mod_vhost_alias (after CVE-2026-63292) This issue affects Apache HTTP Server: 2.4.69.

Why

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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
the affected interface → Stack-based Buffer Overflow → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Unspecified
Privileges required
Not stated in the selected CVSS metric
User interaction
Not stated in the selected CVSS metric
Attack complexity
Not stated in the selected CVSS metric
Security boundary
Not stated in the selected CVSS metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-121 ↗

CWE-121: Stack-based Buffer Overflow. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
Not available from the selected scoring authority.
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.
CWE-121
A

Official authority intelligence

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

BSI · German · WID-SEC-2026-4517Apache HTTP Server: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Apache HTTP Server ausnutzen, um einen Denial of Service Angriff durchzuführen oder beliebigen Programmcode auszuführen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1500Avis du CERT-FR

De multiples vulnérabilités ont été découvertes dans Apache HTTP Server. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service et un problème de sécurité non spécifié par l'éditeur.

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-7073Apache 제품 보안 업데이트 권고

Apache HTTP Server에서 발생하는 Stack-based Buffer Overflow 취약점(CVE-2026-109163) [1][4]

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.
Patch available
Affected
Apache HTTP Server: 2.4.69 ≤ 2.4.70
Fixed
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 11 Nov 2026 · Last source change 11 Nov 2026, 14:55 UTC · CWE-121 · Stack-based Buffer Overflow

CVE recordCVE.org · 5.2
CVSS sourceUnavailable
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-11-12
European sourceNo official EUVD mapping
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

Missing structured fields: CVSS base score. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-109163 to remediation: access.redhat.com/CVE-2026-109163.
    Before
    remediation: access.redhat.com/CVE-2026-109163
    After
    remediation: access.redhat.com/CVE-2026-109163
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Red Hat Product Security ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    httpd.src as a component of Red Hat Hardened Images
    After
    Fixed: httpd-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; httpd-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; httpd-0:2.4.71-0.1.hum1@src as a component of Red Hat Hardened Images; httpd-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; httpd-core-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; httpd-core-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; httpd-core-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; httpd-devel-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; httpd-devel-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; httpd-devel-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; httpd-filesystem-0:2.4.71-0.1.hum1@noarch@public-hummingbird-aarch64-rpms as a component of Red Hat Hardened Images; httpd-filesystem-0:2.4.71-0.1.hum1@noarch@public-hummingbird-s390x-rpms as a component of Red Hat Hardened Images; httpd-filesystem-0:2.4.71-0.1.hum1@noarch@public-hummingbird-x86_64-rpms as a component of Red Hat Hardened Images; httpd-manual-0:2.4.71-0.1.hum1@noarch@public-hummingbird-aarch64-rpms as a component of Red Hat Hardened Images; httpd-manual-0:2.4.71-0.1.hum1@noarch@public-hummingbird-s390x-rpms as a component of Red Hat Hardened Images; httpd-manual-0:2.4.71-0.1.hum1@noarch@public-hummingbird-x86_64-rpms as a component of Red Hat Hardened Images; httpd-tools-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; httpd-tools-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; httpd-tools-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; mod_ldap-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; mod_ldap-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; mod_ldap-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; mod_lua-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; mod_lua-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; mod_lua-0:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; mod_proxy_html-1:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; mod_proxy_html-1:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; mod_proxy_html-1:2.4.71-0.1.hum1@x86_64 as a component of Red Hat Hardened Images; mod_session-0:2.4.71-0.1.hum1@aarch64 as a component of Red Hat Hardened Images; mod_session-0:2.4.71-0.1.hum1@s390x as a component of Red Hat Hardened Images; and 4 more
    Red Hat Product Security ↗
  4. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Vendor CSAF · Red Hat Product Security↗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-2026-109163 · cve.blacktree.nl