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TomcatWeb server / proxy · Apache

CVE-2018-1336

HIGH · 7.5 CVSS v3.1 Published 2018-08-02
Fix available
A fix is available. Upgrade to after 9.0.7 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
An improper handing of overflow in the UTF-8 decoder with supplementary characters can lead to an infinite loop in the decoder causing a Denial of Service. Versions Affected: Apache Tomcat 9.0.0.M9 to 9.0.7, 8.5.0 to 8.5.30, 8.0.0.RC1 to 8.0.51, and 7.0.28 to 7.0.86.

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

Apache Tomcat's UTF-8 decoder improperly handles overflow conditions when processing supplementary Unicode characters (4-byte UTF-8 sequences). This triggers an infinite loop in the decoder, causing the affected request-handling thread to hang and resulting in Denial of Service.

MitigationUpgrade to Apache Tomcat 9.0.8+, 8.5.31+, 8.0.52+, or 7.0.87+ to obtain the patched UTF-8 decoder. No configuration changes or code modifications are required beyond the version upgrade.

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
TomcatWeb server / proxy
Affected:>= 7.0.28, <= 7.0.86>= 8.0.0, <= 8.0.51>= 8.5.0, <= 8.5.30>= 9.0.1, <= 9.0.7= 8.0.0= 9.0.0
Jboss Enterprise Application PlatformApplication
Affected:= 6.0.0= 6.4.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04
Debian LinuxOperating system
Affected:= 8.0= 9.0
Jboss Enterprise Web ServerApplication
Affected:= 3.0.0= 5.0.0
Enterprise Linux DesktopOperating system
Affected:= 7.0
Enterprise Linux ServerOperating system
Affected:= 7.0
Enterprise Linux WorkstationOperating system
Affected:= 7.0

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:3.1/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. Locate Apache Tomcat installation
    Check for Tomcat via environment variable CATALINA_HOME, or look in common installation paths such as /usr/share/tomcat, /opt/tomcat, /etc/tomcat, or the Windows Service GUI if running on Windows. Also check for process named 'catalina.jar' or 'tomcat' running on the system.
    Affected if Tomcat is installed and running.
  2. Determine installed Tomcat version
    Inspect the file ' RELEASE-NOTE' in the Tomcat home directory, or run 'catalina.sh version' if script access is available, or check the server HTTP response header for the Server field which often reveals the version.
    Affected if A Tomcat version is found.
  3. Compare version against affected Apache Tomcat ranges
    Match the identified version number against the following vulnerable ranges: 7.0.28 through 7.0.86 inclusive, 8.0.0 through 8.0.51 inclusive, 8.5.0 through 8.5.30 inclusive, 9.0.1 through 9.0.7 inclusive, plus exact versions 8.0.0 and 9.0.0.
    Affected if The installed version falls within or matches any of these ranges.
  4. Check for Linux distribution bundled Tomcat
    If running Ubuntu 14.04, Ubuntu 16.04, Debian 8.0, Debian 9.0, or Red Hat Enterprise Linux 7.0 (Desktop, Server, or Workstation), determine whether the system uses a packaged Tomcat from the distribution repository or a bundled version that matches the affected ranges.
    Affected if The operating system is one of these versions and ships with or uses a Tomcat version from the affected list.
  5. Check for Red Hat JBoss installations
    If running Red Hat JBoss Enterprise Application Platform 6.0.0 or 6.4.0, or JBoss Enterprise Web Server 3.0.0 or 5.0.0, identify the bundled Tomcat component version included with these products.
    Affected if One of these JBoss products is installed, as they bundle the vulnerable Tomcat version.

The environment is affected if Apache Tomcat (or a product bundling it) is running a version within 7.0.28-7.0.86, 8.0.0-8.0.51, 8.5.0-8.5.30, 9.0.1-9.0.7, or exactly 8.0.0/9.0.0, and the system processes UTF-8 encoded requests containing 4-byte Unicode characters.

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 9.0.7
Interim mitigation

Upgrade to Apache Tomcat 9.0.8+, 8.5.31+, 8.0.52+, or 7.0.87+ to obtain the patched UTF-8 decoder. No configuration changes or code modifications are required beyond the version upgrade.

Fix this in Tomcat 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.

Scan for this in your stack

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dbcve dependency scanner

Check whether your project pulls in CVE-2018-1336 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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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-2018-1336 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