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TomcatWeb server / proxy · Apache

CVE-2026-24880

HIGH · 7.5 CVSS v3.1 Published 2026-04-09
Fix available
A fix is available. Upgrade to 9.0.116 / 10.1.53 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
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat via invalid chunk extension. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.18, from 10.1.0-M1 through 10.1.52, from 9.0.0.M1 through 9.0.115, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Other, unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.20, 10.1.52 or 9.0.116, 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

HTTP Request Smuggling vulnerability in Apache Tomcat where invalid chunk extensions in chunked transfer-encoded requests are not properly validated, allowing attackers to bypass security controls by smuggling malicious requests through the server.

MitigationUpgrade Apache Tomcat to version 11.0.20, 10.1.52, or 9.0.116 (or later) to patch the invalid chunk extension handling vulnerability.

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, < 9.0.116>= 10.1.0, < 10.1.53>= 11.0.0, < 11.0.20

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 version
    Check the version banner in server startup logs or inspect the filename of the downloaded Tomcat archive. The version is also visible in the 'Server number' line from running 'version.sh' (Linux) or 'version.bat' (Windows) in the Tomcat bin directory.
    Affected if The installed version falls within any of these ranges: 9.0.0 through 9.0.115, 10.1.0 through 10.1.52, or 11.0.0 through 11.0.19.
  2. Confirm chunked transfer encoding is enabled
    Inspect the server.xml configuration file in the Tomcat conf directory. Look for <Connector> elements and verify the presence of the 'HTTP/1.1' protocol or the default connector configuration. By default, Tomcat HTTP connectors support chunked transfer encoding.
    Affected if Chunked transfer encoding is enabled in any active HTTP connector configuration.
  3. Check for front-end proxy or load balancer
    Review network architecture documentation or server configuration to determine if a reverse proxy, load balancer, or web server (such as Apache HTTP Server, Nginx, or IIS) sits in front of Tomcat handling HTTP requests.
    Affected if A front-end proxy or load balancer processes HTTP requests before forwarding them to Tomcat, making the environment potentially vulnerable to request smuggling between the proxy and Tomcat.

You are affected if your Tomcat version is below 9.0.116, 10.1.53, or 11.0.20 AND chunked transfer encoding is enabled on an HTTP connector that is accessible either directly or through a front-end proxy.

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 9.0.116 / 10.1.53 / 11.0.20 or later
Fixed in 9.0.11610.1.5311.0.20
Interim mitigation

Upgrade Apache Tomcat to version 11.0.20, 10.1.52, or 9.0.116 (or later) to patch the invalid chunk extension handling vulnerability.

Recommended fix High confidence

Upgrade to Tomcat 9.0.116, 10.1.52, or 11.0.20 depending on your major version branch

  1. 1. Back up your current Tomcat installation directory, including all configuration files, web applications, and any custom libraries.
  2. 2. Stop the Tomcat service or process if it is currently running.
  3. 3. Download the appropriate fixed version of Apache Tomcat: 9.0.116, 10.1.52, or 11.0.20 from the official Apache Tomcat download page (tomcat.apache.org).
  4. 4. Extract the new Tomcat version to a temporary location.
  5. 5. Copy the conf directory from your backup to the new Tomcat installation, preserving custom server.xml, context.xml, and other configuration files.
  6. 6. Copy any custom libraries or deployed web applications from the backup to the new installation if not using a standard deployment directory.
  7. 7. Start the Tomcat service or process and verify the application functions correctly.
  8. 8. Monitor logs for any errors or unexpected behavior after upgrade.
Caveat Review release notes for your version branch for any backward-incompatible changes in configuration or API; test in staging before production deployment

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

Fix this in Tomcat Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2026-24880 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