dbcve.org
HTTP ServerWeb server / proxy · Apache

CVE-2018-17189

MEDIUM · 5.3 CVSS v3.1 Published 2019-01-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
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
In Apache HTTP server versions 2.4.37 and prior, by sending request bodies in a slow loris way to plain resources, the h2 stream for that request unnecessarily occupied a server thread cleaning up that incoming data. This affects only HTTP/2 (mod_http2) connections.

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

A denial of service vulnerability in Apache HTTP Server's mod_http2 where slow loris-style request body uploads to plain (non-h2) resources cause HTTP/2 stream handlers to unnecessarily occupy server threads while cleaning up incoming data, potentially leading to thread exhaustion.

MitigationUpgrade Apache HTTP Server to version 2.4.38 or later, or disable mod_http2 if HTTP/2 is not required.

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:= 2.4.17= 2.4.18= 2.4.20= 2.4.23= 2.4.25= 2.4.26= 2.4.27= 2.4.28= 2.4.29= 2.4.30= 2.4.33= 2.4.34
FedoraOperating system
Affected:= 28= 29
Debian LinuxOperating system
Affected:= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 18.04= 18.10
Jboss Core ServicesApplication
Affected:= 1.0
Santricity Cloud ConnectorApplication
Affected:all versions
Storage Automation StoreApplication
Affected:all versions
Enterprise Manager Ops CenterApplication
Affected:= 12.3.3

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
Low

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

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 installed Apache HTTP Server version
    Run 'httpd -v' or 'apache2 -v' to get the server version number
    Affected if Version matches 2.4.17, 2.4.18, 2.4.20, 2.4.23, 2.4.25, 2.4.26, 2.4.27, 2.4.28, 2.4.29, 2.4.30, 2.4.33, or 2.4.34
  2. Confirm mod_http2 is loaded
    Run 'httpd -M' or 'apache2ctl -M' and look for 'http2_module' in the loaded modules list
    Affected if mod_http2 appears in the loaded modules list
  3. Check if HTTP/2 protocol is enabled
    Inspect the server configuration files (httpd.conf, ssl.conf, or included config files) for 'Protocols h2 h2c' or 'Protocols h2' directives, or check for 'SSLProtocol' with TLS configuration that may enable HTTP/2 via ALPN
    Affected if HTTP/2 protocol (h2 or h2c) is explicitly enabled in the configuration
  4. Verify the server handles non-h2 resources with HTTP/2 enabled
    Confirm the server is configured to handle both HTTP/1.1 and HTTP/2 requests, as the vulnerability triggers when slow request body uploads occur to plain (non-h2) resources while HTTP/2 is enabled
    Affected if The server accepts both HTTP/1.1 and HTTP/2 connections and does not restrict HTTP/2 to specific virtual hosts only

You are affected if you run Apache HTTP Server version 2.4.17 through 2.4.34 with mod_http2 loaded and HTTP/2 protocol enabled, allowing mixed HTTP/1.1 and HTTP/2 request handling.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Apache HTTP Server to version 2.4.38 or later, or disable mod_http2 if HTTP/2 is not required.

Fix this in HTTP Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2018-17189 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