CVE-2026-59083 in Apache Tomcat
Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.24, 10.1.57 or 9.0.120, which fix the issue.
Quick answer
Apache Software Foundation Apache Tomcat should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Apache Tomcat 11.0.0-M1 through 11.0.23
- Apache Tomcat 10.1.0-M1 through 10.1.56
- Apache Tomcat 9.0.0-M1 through 9.0.119
- Apache Tomcat 8.5.0 through 8.5.100
Fixed versions
- Apache Tomcat 11.0.24 or later
- Apache Tomcat 10.1.57 or later
- Apache Tomcat 9.0.120 or later
How to fix it
CVE-2026-59083 affects Apache Tomcat. In simple terms, the affected software may be used in an unsafe way. Fix it by updating to Apache Tomcat 11.0.24 or later; Apache Tomcat 10.1.57 or later; Apache Tomcat 9.0.120 or later. If this system is online or used by admins, treat the fix as important.
- Find every place where Apache Tomcat is installed or used.
- Check if the version matches: Apache Tomcat 11.0.0-M1 through 11.0.23; Apache Tomcat 10.1.0-M1 through 10.1.56; Apache Tomcat 9.0.0-M1 through 9.0.119; Apache Tomcat 8.5.0 through 8.5.100.
- Update or apply the vendor fix: Apache Tomcat 11.0.24 or later; Apache Tomcat 10.1.57 or later; Apache Tomcat 9.0.120 or later.
- If you cannot update today, allow only trusted users and trusted networks.
- Turn off the affected feature or plugin if the vendor says that is safe to do.
- Check logs for crashes, strange requests, new admin actions, or unexpected access.
- Change secrets or passwords if you think data or admin access may have been exposed.
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Verify the fix
- Confirm the installed version or mitigation matches: Apache Tomcat 11.0.24 or later; Apache Tomcat 10.1.57 or later; Apache Tomcat 9.0.120 or later.
- Confirm the affected feature is no longer exposed to untrusted users.
- Run the affected workflow again and make sure it still works.
- Review logs again after the fix for repeated suspicious activity.
- Run a new Fixnx scan if this software is part of a public website.
- Save the advisory link and proof of the fix in your change record.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-59083?
Apache Software Foundation Apache Tomcat versions listed as affected should be reviewed: Apache Tomcat 11.0.0-M1 through 11.0.23, Apache Tomcat 10.1.0-M1 through 10.1.56, Apache Tomcat 9.0.0-M1 through 9.0.119, Apache Tomcat 8.5.0 through 8.5.100.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.