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Jboss Wildfly Application ServerApplication · Redhat

CVE-2016-9589

HIGH · 7.5 CVSS v3.0 Published 2018-03-12
Fix available
A fix is available. Upgrade to after 10.1.0 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
Undertow in Red Hat wildfly before version 11.0.0.Beta1 is vulnerable to a resource exhaustion resulting in a denial of service. Undertow keeps a cache of seen HTTP headers in persistent connections. It was found that this cache can easily exploited to fill memory with garbage, up to "max-headers" (default 200) * "max-header-size" (default 1MB) per active TCP connection.

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

Undertow in Wildfly before 11.0.0.Beta1 maintains a cache of HTTP headers for persistent connections. This cache is vulnerable to resource exhaustion because an attacker can fill it with garbage data, consuming up to max-headers (default 200) times max-header-size (default 1MB) = 200MB per active TCP connection, leading to denial of service.

MitigationUpgrade Wildfly to version 11.0.0.Beta1 or later to obtain the patched Undertow component, or apply configuration limits to max-headers and max-header-size to reduce the memory exhaustion potential per connection.

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
Jboss Wildfly Application ServerApplication
Affected:<= 10.1.0= 11.0.0

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 Wildfly version
    Locate the Wildfly installation and check the version. Common locations: check the 'jboss-modules.jar' or 'wildfly.jar' in the installation root, or run 'grep -r "WildFly" <install_dir>/modules' or check server log startup banner
    Affected if Version is 10.1.0 or lower, or exactly version 11.0.0 (unpatched Beta1)
  2. Confirm Undertow is the HTTP connector
    Check the standalone.xml configuration file (typically in <wildfly_dir>/standalone/configuration/) for <server name="default-server"> section. Look for <http-listener> entries that use Undertow. The vulnerability exists in the Undertow HTTP listener.
    Affected if Undertow is configured as the HTTP listener (default in Wildfly 8+)
  3. Inspect max-header-size configuration
    In standalone.xml, find the http-listener element and check the 'max-header-size' attribute. If not present, it defaults to 1MB (1048576 bytes). Example path: /subsystem=undertow/server=default-server/http-listener=default
    Affected if max-header-size is set to default 1MB or a large value, creating potential for large memory allocation per connection
  4. Inspect max-headers configuration
    In standalone.xml, find the <host> element under <subsystem xmlns="urn:jboss:domain:undertow:..."> and check the 'max-headers' attribute. If not present, it defaults to 200. Example: /subsystem=undertow/server=default-server/host=default-host
    Affected if max-headers is set to default 200 or a high value, allowing many headers per connection
  5. Determine network exposure
    Check if the Wildfly HTTP listener is bound to a public or untrusted network interface. Look for 'bind-address' in standalone.xml or the -b startup parameter. Check firewall rules and network ACLs controlling access to the HTTP port (default 8080)
    Affected if HTTP interface is exposed to untrusted networks without proper access controls, enabling remote attackers to trigger the resource exhaustion

You are affected if running Wildfly version 10.1.0 or lower, or exactly 11.0.0, with Undertow exposed to untrusted networks and default or large max-headers/max-header-size settings.

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 10.1.0
Interim mitigation

Upgrade Wildfly to version 11.0.0.Beta1 or later to obtain the patched Undertow component, or apply configuration limits to max-headers and max-header-size to reduce the memory exhaustion potential per connection.

Fix this in Jboss Wildfly Application Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

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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-2016-9589 in production — separate from our analysis above.

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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
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