CVE-2026-43513: Apache Tomcat: LockOutRealm treats user names as case-sensitive

Published May 12, 2026
·
Updated

Improper Handling of Case Sensitivity vulnerability in LockOutRealm in Apache Tomcat.

Affected Software

10 affected componentsFixes available
Apache Tomcat>=11.0.0-M1<=11.0.21, >=10.1.0-M1<=10.1.54, >=9.0.0.M1<=9.0.117, >=8.5.0<=8.5.100, >=7.0.0<=7.0.109
Apache Tomcat>=7.0.0<=7.0.109
Apache Tomcat>=8.5.0<=8.5.100
Apache Tomcat>=9.0.0<9.0.118
Apache Tomcat>=10.1.0<10.1.55
Apache Tomcat>=11.0.0<11.0.22
debian/tomcat10<=10.1.52-1~deb12u1, <=10.1.52-1~deb13u1
10.1.55-1~deb12u110.1.55-1~deb13u110.1.55-1
debian/tomcat11<=11.0.15-1~deb13u1, <=11.0.21-1
11.0.22-1~deb13u111.0.22-2
debian/tomcat9<=9.0.43-2~deb11u10
9.0.118-0+deb11u19.0.70-29.0.95-19.0.118-1
IBM API Connect V12 OnPrem<=All

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade debian/tomcat10 to a version that resolves this vulnerability.

    Fixed in 10.1.55-1~deb12u1Fixed in 10.1.55-1~deb13u1Fixed in 10.1.55-1
  2. Upgrade

    Upgrade debian/tomcat11 to a version that resolves this vulnerability.

    Fixed in 11.0.22-1~deb13u1Fixed in 11.0.22-2
  3. Upgrade

    Upgrade debian/tomcat9 to a version that resolves this vulnerability.

    Fixed in 9.0.118-0+deb11u1Fixed in 9.0.70-2Fixed in 9.0.95-1Fixed in 9.0.118-1
  4. Upgrade

    Upgrade Apache Tomcat to a version that resolves this vulnerability.

    Fixed in 11.0.22
  5. Upgrade

    Upgrade Apache Tomcat to a version that resolves this vulnerability.

    Fixed in 10.1.55
  6. Upgrade

    Upgrade Apache Tomcat to a version that resolves this vulnerability.

    Fixed in 9.0.118

Event History

May 12, 2026
CVE Published
via MITRE·03:26 PM
Data Sourced
via MITRE·03:26 PM
DescriptionWeakness
Data Sourced
via Red Hat·04:02 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·04:16 PM
DescriptionSeverityWeaknessAffected Software
Jun 10, 2026
Data Sourced
via Ubuntu·10:09 AM
RemedyDescriptionSeverityAffected Software
Data Sourced
via Launchpad·10:10 AM
Description
Data Sourced
via Debian·10:12 AM
DescriptionAffected Software
Jul 7, 2026
Data Sourced
via IBM·12:00 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

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Frequently Asked Questions

1

What is the severity of CVE-2026-43513?

CVE-2026-43513 has been categorized as a medium-severity vulnerability due to its potential impact on user authentication.

2

How do I fix CVE-2026-43513?

To fix CVE-2026-43513, upgrade to the latest version of Apache Tomcat that has addressed this case sensitivity issue in the LockOutRealm.

3

Which versions of Apache Tomcat are affected by CVE-2026-43513?

CVE-2026-43513 affects Apache Tomcat versions 7.0.0 to 7.0.109, 8.5.0 to 8.5.100, 9.0.0.M1 to 9.0.117, 10.1.0-M1 to 10.1.54, and 11.0.0-M1 to 11.0.21.

4

What components are involved in CVE-2026-43513?

CVE-2026-43513 specifically involves the LockOutRealm component in Apache Tomcat which improperly handles case sensitivity in usernames.

5

Is there a workaround for CVE-2026-43513?

Currently, there are no official workarounds provided for CVE-2026-43513, so upgrading to a patched version is recommended.

Company

Resources

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