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TomcatWeb server / proxy · Apache

CVE-2025-52434

HIGH · 7.5 CVSS v3.1 Published 2025-07-10
Fix available
A fix is available. Upgrade to 9.0.107 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
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in Apache Tomcat when using the APR/Native connector. This was particularly noticeable with client initiated closes of HTTP/2 connections. This issue affects Apache Tomcat: from 9.0.0.M1 through 9.0.106. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 through 8.5.100. Other, older, EOL versions may also be affected. Users are recommended to upgrade to version 9.0.107, 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

Race condition vulnerability in Apache Tomcat's APR/Native connector during HTTP/2 connection handling. When clients close HTTP/2 connections, improper synchronization of shared resources can occur, potentially leading to undefined behavior or denial of service.

MitigationUpgrade to Apache Tomcat 9.0.107 or later (or 8.5.101+ for 8.5 line) which contains the fix. If upgrade is not immediately feasible, consider using the NIO connector instead of APR/Native for HTTP/2 traffic as a temporary workaround.

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, < 9.0.107

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. Identify Apache Tomcat version
    Check the version displayed in the Tomcat startup logs, or look in the RELEASE-NOTES file in the Tomcat home directory, or run: java -cp catalina.jar org.apache.catalina.util.ServerInfo
    Affected if The installed version is 9.0.0 through 9.0.106 inclusive
  2. Confirm APR/Native connector is in use
    Inspect the server.xml configuration file (typically in conf/ directory) and look for an <Connector> element with protocol="org.apache.coyote.http11.Http11AprProtocol" or a connector that loads the APR/native library. Also check if the server.xml defines an APRConnector.
    Affected if The server.xml uses the APR/Native connector protocol for HTTP traffic
  3. Verify HTTP/2 is enabled
    Check the same server.xml for an <UpgradeProtocol> element with protocolClassName="org.apache.coyote.http2.Http2Protocol" nested within the APR/Native connector, or check for an HTTP/2 upgrade configuration on the connector
    Affected if HTTP/2 protocol upgrade is configured on the APR/Native connector

You are affected if you run Apache Tomcat 9.0.0-9.0.106 with both the APR/Native connector and HTTP/2 protocol 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 9.0.107 or later
Fixed in 9.0.107
Interim mitigation

Upgrade to Apache Tomcat 9.0.107 or later (or 8.5.101+ for 8.5 line) which contains the fix. If upgrade is not immediately feasible, consider using the NIO connector instead of APR/Native for HTTP/2 traffic as a temporary workaround.

Recommended fix High confidence

9.0.107 (for Tomcat 9.x); Tomcat 8.5.x is EOL, upgrade to 9.0.107+

  1. 1. Identify the currently running Apache Tomcat version using the bin/version.sh (Unix) or bin\version.bat (Windows) script
  2. 2. If running Tomcat 9.0.0 through 9.0.106, upgrade to Tomcat 9.0.107 from the official Apache Tomcat downloads page (tomcat.apache.org)
  3. 3. If running Tomcat 8.5.x (8.5.0 through 8.5.100), note that this version branch is EOL; upgrade to Tomcat 9.0.107 or later for continued support
  4. 4. Deploy the new Tomcat version in your environment, replacing the vulnerable installation
  5. 5. Verify the APR/Native connector configuration if using HTTP/2 with the APR connector
  6. 6. Test HTTP/2 connections and client-initiated closes to confirm the race condition is resolved
  7. 7. Monitor for any regressions in application functionality
Caveat Minimal expected; Tomcat minor version upgrades typically maintain backward compatibility

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

Fix this in Tomcat Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2025-52434 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
  • No spam, self-promotion, credentials, or personal data