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TomcatWeb server / proxy · Apache

CVE-2024-56337

CRITICAL · 9.8 CVSS v3.1 Published 2024-12-20
Fix available
A fix is available. Upgrade to 9.0.98 / 10.1.34 or later.
See remediation →
100/100
Remediation priority · Urgent
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
Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.1, from 10.1.0-M1 through 10.1.33, from 9.0.0.M1 through 9.0.97. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100. Other, older, EOL versions may also be affected. The mitigation for CVE-2024-50379 was incomplete. Users running Tomcat on a case insensitive file system with the default servlet write enabled (readonly initialisation parameter set to the non-default value of false) may need additional configuration to fully mitigate CVE-2024-50379 depending on which version of Java they are using with Tomcat: - running on Java 8 or Java 11: the system property sun.io.useCanonCaches must be explicitly set to false (it defaults to true) - running on Java 17: the system property sun.io.useCanonCaches, if set, must be set to false (it defaults to false) - running on Java 21 onwards: no further configuration is required (the system property and the problematic cache have been removed) Tomcat 11.0.3, 10.1.35 and 9.0.99 onwards will include checks that sun.io.useCanonCaches is set appropriately before allowing the default servlet to be write enabled on a case insensitive file system. Tomcat will also set sun.io.useCanonCaches to false by default where it can.

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

TOCTOU race condition in Apache Tomcat's default servlet (incomplete fix for CVE-2024-50379). On case-insensitive file systems with write-enabled default servlet (readonly=false), a race condition exists in file path canonicalization that can be exploited to bypass security checks.

MitigationUpgrade to Tomcat 11.0.3+, 10.1.35+, or 9.0.99+. Additionally, set JVM system property sun.io.useCanonCaches=false when running on Java 8, 11, or 17 with case-insensitive file systems.

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:>= 9.0.0, < 9.0.98>= 10.1.0, < 10.1.34>= 11.0.0, < 11.0.2
Bootstrap OsOperating system
Affected:all versions

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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. Check Apache Tomcat version
    Locate the Tomcat installation and identify the version number (typically in a VERSION file or the release notes within the installation directory). Compare this version against the affected ranges: 9.0.0 to 9.0.97, 10.1.0 to 10.1.33, or 11.0.0 to 11.0.1.
    Affected if The installed version falls within any of the affected version ranges.
  2. Verify default servlet write configuration
    Examine the Tomcat default servlet configuration (typically in conf/web.xml or within a application's web.xml) for the 'readonly' parameter setting.
    Affected if The 'readonly' parameter is explicitly set to 'false', enabling write operations.
  3. Identify the operating system file system type
    Determine the underlying file system for the Tomcat web root directory. On Windows, most file systems (NTFS, FAT32) are case-insensitive. On macOS, APFS and HFS+ are case-insensitive by default. On Linux, verify if the filesystem is mounted as case-insensitive.
    Affected if The Tomcat web application directories reside on a case-insensitive file system.
  4. Check Java canon path caching property
    Inspect the Java runtime system properties, specifically 'sun.io.useCanonCaches'. This can be done via the Java control panel, startup scripts, or by adding a diagnostic servlet that outputs System.getProperty("sun.io.useCanonCaches").
    Affected if The property 'sun.io.useCanonCaches' is set to 'true' (the default on some Java versions) and the application uses concurrent file operations.

You are likely affected if your Tomcat version is in the vulnerable range, the default servlet has readonly=false, and your web root is on a case-insensitive file system with canon path caching enabled.

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 9.0.98 / 10.1.34 / 11.0.2 or later
Fixed in 9.0.9810.1.3411.0.2
Interim mitigation

Upgrade to Tomcat 11.0.3+, 10.1.35+, or 9.0.99+. Additionally, set JVM system property sun.io.useCanonCaches=false when running on Java 8, 11, or 17 with case-insensitive file systems.

Recommended fix High confidence

Tomcat 9.0.99 (for 9.0.x), 10.1.35 (for 10.1.x), or 11.0.3 (for 11.0.x)

  1. 1. Identify the current Tomcat version in use (9.0.x, 10.1.x, or 11.0.x) and the Java version (java -version)
  2. 2. Plan an upgrade to the appropriate fixed release: Tomcat 9.0.99+, 10.1.35+, or 11.0.3+
  3. 3. Before upgrading, if staying on an affected version is necessary, determine if the default servlet write is enabled (readonly=false) on a case-insensitive file system
  4. 4. If using an affected version with write-enabled default servlet on case-insensitive file system: for Java 8 or 11, add -Dsun.io.useCanonCaches=false to JAVA_OPTS or CATALINA_OPTS; for Java 17, ensure sun.io.useCanonCaches is not set or is set to false
  5. 5. Test the upgrade in a non-production environment first
  6. 6. After upgrading to 9.0.99+, 10.1.35+, or 11.0.3+, Tomcat will validate the sun.io.useCanonCaches setting automatically
Caveat Minor: Tomcat now enforces validation of sun.io.useCanonCaches on case-insensitive file systems when write-enabled; ensure any existing scripts setting this property use the correct value (false)

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

Fix this in Tomcat 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-2024-56337 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
  • No weaponised exploit code, or anything meant to cause harm
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