dbcve.org
TomcatWeb server / proxy · Apache

CVE-2023-42794

MEDIUM · 5.9 CVSS v3.1 Published 2023-10-10
Fix available
A fix is available. Upgrade to 8.5.94 / 9.0.81 or later.
See remediation →
68/100
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
Incomplete Cleanup vulnerability in Apache Tomcat. The internal fork of Commons FileUpload packaged with Apache Tomcat 9.0.70 through 9.0.80 and 8.5.85 through 8.5.93 included an unreleased, in progress refactoring that exposed a potential denial of service on Windows if a web application opened a stream for an uploaded file but failed to close the stream. The file would never be deleted from disk creating the possibility of an eventual denial of service due to the disk being full. Other, EOL versions may also be affected. Users are recommended to upgrade to version 9.0.81 onwards or 8.5.94 onwards, which fixes 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

A vulnerability in the internal fork of Commons FileUpload bundled with Apache Tomcat 9.0.70-9.0.80 and 8.5.85-8.5.93 leaves uploaded files undeleted when application streams aren't properly closed, potentially causing disk exhaustion and denial of service on Windows systems.

MitigationUpgrade to Apache Tomcat 9.0.81 or later, or 8.5.94 or later to resolve this issue.

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:>= 8.5.85, < 8.5.94>= 9.0.70, < 9.0.81

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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 Tomcat version
    Check the VERSION file in the Tomcat installation directory, or look for the version in the server startup logs. On Linux/Unix, you can also run: grep -r "Apache Tomcat" $CATALINA_HOME/LICENSE or check RELEASE-NOTES file.
    Affected if The installed version is 8.5.85 through 8.5.93, or 9.0.70 through 9.0.80.
  2. Confirm operating system
    Check if the Tomcat server is running on Windows. Run 'uname -a' on Linux/Unix or check System Properties on Windows.
    Affected if The server is running on Windows, as the file undeletion issue specifically causes disk exhaustion on this OS.
  3. Verify file upload is in use
    Review the application deployed on Tomcat to determine if it uses Commons FileUpload or standard Servlet 3.0 multipart requests for handling file uploads. Check web.xml for any multipart-config or look for file upload related code in the deployed applications.
    Affected if The deployed application uses file upload functionality via Tomcat's Commons FileUpload or Servlet multipart requests.
  4. Inspect temp directory for orphaned files
    On Windows, check the Tomcat temp directory (default is %CATALINA_HOME%\temp or the directory specified by java.io.tmpdir) for any accumulating uploaded files. List files and note their age and size.
    Affected if Large numbers of undeleted uploaded files are present in the temp directory, indicating the vulnerability has been triggered.

You are affected if your Tomcat version falls within 8.5.85-8.5.93 or 9.0.70-9.0.80, you are running on Windows, and your application handles file uploads, resulting in orphaned temp files.

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 8.5.94 / 9.0.81 or later
Fixed in 8.5.949.0.81
Interim mitigation

Upgrade to Apache Tomcat 9.0.81 or later, or 8.5.94 or later to resolve this issue.

Recommended fix High confidence

Apache Tomcat 8.5.94 (or later 8.5.x) or 9.0.81 (or later 9.0.x)

  1. Identify the currently running Tomcat version (8.5.x or 9.0.x branch)
  2. Stop the Tomcat service or instance
  3. Backup the entire Tomcat installation directory including conf/ and webapps/
  4. Download the fixed version: Apache Tomcat 8.5.94 or later, or 9.0.81 or later from https://tomcat.apache.org/
  5. Extract the new Tomcat version to a temporary location
  6. Copy the new Tomcat binaries to replace the old installation
  7. Restore the conf/ directory (server.xml, context.xml, etc.) from the backup
  8. Restore deployed applications from the backup if not using a separate webapps directory
Caveat Tomcat minor version upgrades are typically backward compatible; however, review the release notes for any configuration or API changes between your current version and the upgrade 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
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-42794 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2023-42794 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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