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HTTP ServerWeb server / proxy · Apache

CVE-2018-1333

HIGH · 7.5 CVSS v3.0 Published 2018-06-18
Fix available
A fix is available. Upgrade to after 2.4.30 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
By specially crafting HTTP/2 requests, workers would be allocated 60 seconds longer than necessary, leading to worker exhaustion and a denial of service. Fixed in Apache HTTP Server 2.4.34 (Affected 2.4.18-2.4.30,2.4.33).

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 · high confidence

In Apache HTTP Server 2.4.18-2.4.33, specially crafted HTTP/2 requests cause workers to be allocated 60 seconds longer than necessary. This extended worker retention combined with repeated requests leads to worker pool exhaustion and results in denial of service.

MitigationUpgrade Apache HTTP Server to version 2.4.34 or later. If immediate patching is not possible, consider limiting HTTP/2 connections or implementing rate limiting at the load balancer or firewall level.

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:>= 2.4.18, <= 2.4.30= 2.4.33
Jboss Core ServicesApplication
Affected:= 1.0
Ubuntu LinuxOperating system
Affected:= 18.04
Cloud BackupApplication
Affected:all versions
Storage Automation StoreApplication
Affected:all versions

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:3.0/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. Identify Apache HTTP Server version
    Run 'httpd -v' or 'apache2 -v' to get the installed version number
    Affected if Version is 2.4.18 through 2.4.30, or exactly 2.4.33
  2. Confirm HTTP/2 module is loaded
    Check for 'LoadModule http2_module' in the Apache configuration or run 'httpd -M' / 'apache2ctl -M' to list loaded modules
    Affected if The mod_http2 module is loaded and active
  3. Verify HTTP/2 protocol is enabled
    Search configuration files (httpd.conf, apache2.conf, included conf files) for 'Protocols h2 h2c' or 'Protocols h2' directives
    Affected if HTTP/2 protocol is explicitly enabled in the server configuration
  4. Check worker pool configuration
    Inspect Apache configuration for 'ThreadsPerChild', 'MaxRequestWorkers', 'MaxConnectionsPerChild' settings to understand worker allocation
    Affected if Worker pool settings are at default values (vulnerable to exhaustion under sustained HTTP/2 load)
  5. For affected products (Ubuntu 18.04, JBoss Core Services 1.0, NetApp products)
    Determine if the product bundles Apache HTTP Server and check its version using the methods above
    Affected if The bundled Apache version falls within the affected range and HTTP/2 is in use

Your environment is affected if you are running Apache HTTP Server 2.4.18-2.4.30 or 2.4.33 (or products bundling these versions) with the HTTP/2 protocol enabled.

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.

From vendor data
Upgrade available Upgrade to a release after 2.4.30
Interim mitigation

Upgrade Apache HTTP Server to version 2.4.34 or later. If immediate patching is not possible, consider limiting HTTP/2 connections or implementing rate limiting at the load balancer or firewall level.

Fix this in HTTP Server Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

Scan for this in your stack

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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-2018-1333 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