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HTTP ServerWeb server / proxy · Ibm

CVE-2026-8852

HIGH · 7.5 CVSS v3.1 Published 2026-05-26
Fix available
A fix is available. Upgrade to 8.5.5.30 / 9.0.5.29 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
IBM HTTP Server 8.5, and 9.0 is vulnerable to denial of service via the optional module mod_fastcgi module.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

IBM HTTP Server versions 8.5 and 9.0 contains a denial of service vulnerability in the optional mod_fastcgi module. The vulnerability can be exploited to cause the server to become unavailable, likely through malformed requests or resource exhaustion via the FastCGI handler.

MitigationDisable the mod_fastcgi module if not required, or apply vendor-supplied patches/updates for IBM HTTP Server when available. If FastCGI functionality is needed, restrict access and monitor for abuse.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
HTTP ServerWeb server / proxy
Affected:>= 8.5.0.0, < 8.5.5.30>= 9.0.0.0, < 9.0.5.29

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify if mod_fastcgi module is loaded
    Check the IBM HTTP Server configuration files (httpd.conf or included conf files) for lines containing 'LoadModule fastcgi_module' or 'LoadModule mod_fastcgi'. On AIX, also check the module path /opt/IBM/HTTPServer/modules/ for the presence of mod_fastcgi.so.
    Affected if mod_fastcgi is loaded and the module is actively being used in the configuration
  2. Identify the installed IBM HTTP Server version
    Run the command '/opt/IBM/HTTPServer/bin/httpd -v' or on Windows 'C:\Program Files\IBM\HTTPServer\bin\httpd.exe -v'. This displays the compiled version information.
    Affected if The reported version falls within 8.5.0.0 through 8.5.5.29 OR 9.0.0.0 through 9.0.5.28 (the patched versions are 8.5.5.30 and 9.0.5.29)
  3. Confirm FastCGI directive usage in configuration
    Search all .conf files for FastCGI-related directives such as 'FastCgiServer', 'FastCgiConfig', 'FastCgiIpcDir', or 'FastCgiExternalServer'. Grep command example: 'grep -r "FastCgi" /opt/IBM/HTTPServer/conf/'
    Affected if FastCGI directives are present and the module is configured for processing requests
  4. Check active listen ports and bindings
    Review Listen directives and VirtualHost configurations to identify which ports accept FastCGI-processed requests. This determines the exposure vector for remote attackers.
    Affected if The server listens on network-accessible ports with FastCGI handling enabled

The environment is affected only if IBM HTTP Server version is 8.5.0.0-8.5.5.29 or 9.0.0.0-9.0.5.28 AND the mod_fastcgi module is loaded and configured to handle requests.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.5.5.30 / 9.0.5.29 or later
Fixed in 8.5.5.309.0.5.29
Interim mitigation

Disable the mod_fastcgi module if not required, or apply vendor-supplied patches/updates for IBM HTTP Server when available. If FastCGI functionality is needed, restrict access and monitor for abuse.

Recommended fix High confidence

IBM HTTP Server 8.5.5.30 or later (8.x line); IBM HTTP HTTP Server 9.0.5.29 or later (9.x line)

  1. Identify the currently installed IBM HTTP Server version using 'gsi -version' or checking the installation directory
  2. For IBM HTTP Server 8.5.x: upgrade to version 8.5.5.30 or later
  3. For IBM HTTP Server 9.0.x: upgrade to version 9.0.5.29 or later
  4. Obtain the fix from IBM Fix Central (https://www.ibm.com/support/fixcentral/) or through your IBM entitled container/entitlement
  5. Apply the upgrade following standard IBM HTTP Server upgrade procedures
  6. Verify the installation by checking the new version number
  7. As an alternative mitigation, if mod_fastcgi is not required, consider disabling the mod_fastcgi module in the configuration
Caveat Standard IBM HTTP Server upgrade considerations apply - review IBM's migration guide for compatibility notes and ensure custom configurations are tested

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in HTTP Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8852 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data