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TomcatWeb server / proxy · Apache

CVE-2023-46589

HIGH · 7.5 CVSS v3.1 Published 2023-11-28
Fix available
A fix is available. Upgrade to 8.5.96 / 9.0.83 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
Improper Input Validation vulnerability in Apache Tomcat.Tomcat from 11.0.0-M1 through 11.0.0-M10, from 10.1.0-M1 through 10.1.15, from 9.0.0-M1 through 9.0.82 and from 8.5.0 through 8.5.95 did not correctly parse HTTP trailer headers. A trailer header that exceeded the header size limit could cause Tomcat to treat a single request as multiple requests leading to the possibility of request smuggling when behind a reverse proxy. Older, EOL versions may also be affected. Users are recommended to upgrade to version 11.0.0-M11 onwards, 10.1.16 onwards, 9.0.83 onwards or 8.5.96 onwards, which fix the issue.

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

Improper input validation in Apache Tomcat's HTTP trailer header parsing. When trailer headers exceed the header size limit, Tomcat may incorrectly treat a single HTTP request as multiple requests, enabling request smuggling attacks when Tomcat is deployed behind a reverse proxy.

MitigationUpgrade to Tomcat 11.0.0-M11, 10.1.16, 9.0.83, or 8.5.96 or later versions to fix the improper trailer header parsing that enables request smuggling.

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:>= 8.5.0, < 8.5.96>= 9.0.0, < 9.0.83>= 10.1.0, < 10.1.16= 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
High
Availability
None

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

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 Tomcat installation
    Locate the Tomcat installation directory and check for the presence of the 'catalina.sh' script or 'catalina.bat' file in the 'bin' folder. Common paths include /opt/tomcat, /usr/share/tomcat, or C:\Program Files\Apache\Tomcat.
    Affected if Tomcat is not installed on the system.
  2. Determine installed Tomcat version
    Run the version command from the Tomcat bin directory: 'catalina.sh version' (Linux/Mac) or 'catalina.bat version' (Windows). Look for the Server version number in the output.
    Affected if The installed version falls within any of these ranges: 8.5.0 to 8.5.95, 9.0.0 to 9.0.82, 10.1.0 to 10.1.15, or exactly 11.0.0.
  3. Verify reverse proxy configuration
    Examine the server configuration files (server.xml) and any proxy configuration files (such as Apache httpd.conf, nginx.conf, or load balancer configs) to determine if Tomcat is deployed behind a reverse proxy, load balancer, or other HTTP frontend.
    Affected if Tomcat is directly exposed to clients without a reverse proxy, as the smuggling attack specifically requires a reverse proxy in front of Tomcat.
  4. Check HTTP connector configuration
    Review the <Connector> elements in the server.xml file within the Tomcat conf directory. Look for any 'maxHttpHeaderSize' or similar header limit settings that control trailer header processing.
    Affected if HTTP connectors are configured without proper trailer header limits, and the configuration allows large trailer headers to be processed.

You are affected if Tomcat is installed and running a version within 8.5.0-8.5.95, 9.0.0-9.0.82, 10.1.0-10.1.15, or 11.0.0, and it is deployed behind a reverse proxy that forwards requests to Tomcat.

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 8.5.96 / 9.0.83 / 10.1.16 or later
Fixed in 8.5.969.0.8310.1.16
Interim mitigation

Upgrade to Tomcat 11.0.0-M11, 10.1.16, 9.0.83, or 8.5.96 or later versions to fix the improper trailer header parsing that enables request smuggling.

Recommended fix High confidence

Apache Tomcat 8.5.96+, 9.0.83+, 10.1.16+, or 11.0.0-M11+

  1. 1. Identify the current Apache Tomcat version by checking the $CATALINA_HOME/README file or running 'catalina.sh version'
  2. 2. Download the appropriate fixed version from https://tomcat.apache.org/download-80.cgi, https://tomcat.apache.org/download-90.cgi, https://tomcat.apache.org/download-10.cgi, or https://tomcat.apache.org/download-11.cgi depending on your major version line
  3. 3. Stop the Tomcat service: systemctl stop tomcat or the equivalent for your setup
  4. 4. Back up the entire Tomcat installation directory including conf/ with all configuration files
  5. 5. Extract the new Tomcat version to a temporary location
  6. 6. Copy the conf/ directory from your backup to the new Tomcat installation, preserving your existing configuration
  7. 7. Copy or migrate any deployed web applications from the old webapps/ directory to the new installation
  8. 8. Start the Tomcat service: systemctl start tomcat
Caveat Minor: Review release notes for any behavior changes between your current version and the upgrade target; ensure any custom configurations in server.xml are compatible with the new version

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

Fix this in Tomcat Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing8.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,320
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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-2023-46589 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