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

0
High
VulnerabilityCVE-2026-43513gcveosvubuntu-cve-2026-43513ubuntu-pro-14-04-ltsubuntu-pro-16-04-ltsubuntu-pro-18-04-ltsubuntu-pro-20-04-ltsubuntu-pro-22-04-ltsubuntu-pro-24-04-ltsubuntu-25-10ubuntu-26-04-ltscsafcve-2026-43513red-hat-product-securitybit-tomcat-2026-43513bitnami
Published: 05/14/2026 (05/14/2026, 11:56:47 UTC)
Source: GCVE Database
Product: tomcat

Description

Apache Tomcat's LockOutRealm component improperly handles case sensitivity in user names, allowing remote attackers to potentially bypass account lockout protections and obtain sensitive information. This vulnerability affects multiple versions of Apache Tomcat, including 11.0.0 through 11.0.21, 10.1.0 through 10.1.54, 9.0.0 through 9.0.117, 8.5.0 through 8.5.100, and 7.0.0 through 7.0.109. Official patches are available in versions 11.0.22, 10.1.55, and 9.0.118. Users are advised to update to these fixed versions and restart Tomcat to apply the changes.

Affected software

Ubuntu:Pro:14.04:LTSmore threats →ghsa
tomcat6
pkg:deb/ubuntu/[email protected]+esm3?arch=source&distro=esm-infra-legacy/trusty
Affected versions
<6.0.39-1ubuntu0.1+esm3=6.0.37-1=6.0.39-1=6.0.39-1ubuntu0.1=6.0.39-1ubuntu0.1+esm1=6.0.39-1ubuntu0.1+esm2
Ubuntu:Pro:14.04:LTSmore threats →ghsa
tomcat7
pkg:deb/ubuntu/[email protected]+esm2?arch=source&distro=esm-infra-legacy/trusty
Affected versions
<7.0.52-1ubuntu0.16+esm2=7.0.42-1=7.0.47-1=7.0.50-1=7.0.52-1=7.0.52-1ubuntu0.1=7.0.52-1ubuntu0.3=7.0.52-1ubuntu0.6=7.0.52-1ubuntu0.7=7.0.52-1ubuntu0.8=7.0.52-1ubuntu0.9=7.0.52-1ubuntu0.10=7.0.52-1ubuntu0.11=7.0.52-1ubuntu0.13=7.0.52-1ubuntu0.14=7.0.52-1ubuntu0.15=7.0.52-1ubuntu0.16=7.0.52-1ubuntu0.16+esm1
Ubuntu:Pro:16.04:LTSmore threats →ghsa
tomcat8
pkg:deb/ubuntu/[email protected]+esm2?arch=source&distro=esm-infra-legacy/xenial
Affected versions
=8.0.26-1=8.0.28-1=8.0.30-1=8.0.32-1=8.0.32-1ubuntu1=8.0.32-1ubuntu1.1=8.0.32-1ubuntu1.2=8.0.32-1ubuntu1.3=8.0.32-1ubuntu1.4=8.0.32-1ubuntu1.5=8.0.32-1ubuntu1.6=8.0.32-1ubuntu1.7=8.0.32-1ubuntu1.8=8.0.32-1ubuntu1.9=8.0.32-1ubuntu1.10=8.0.32-1ubuntu1.11=8.0.32-1ubuntu1.13=8.0.32-1ubuntu1.13+esm1=8.0.32-1ubuntu1.13+esm2
Ubuntu:Pro:16.04:LTSmore threats →ghsa
tomcat7
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-apps-legacy/xenial
Affected versions
<7.0.68-1ubuntu0.4+esm4=7.0.64-1=7.0.68-1=7.0.68-1ubuntu0.1=7.0.68-1ubuntu0.3=7.0.68-1ubuntu0.4=7.0.68-1ubuntu0.4+esm1=7.0.68-1ubuntu0.4+esm2=7.0.68-1ubuntu0.4+esm3
Ubuntu:Pro:18.04:LTSmore threats →ghsa
tomcat8
pkg:deb/ubuntu/[email protected]~18.04.3+esm6?arch=source&distro=esm-apps/bionic
Affected versions
=8.5.21-1ubuntu1=8.5.29-1=8.5.30-1=8.5.30-1ubuntu1=8.5.30-1ubuntu1.2=8.5.30-1ubuntu1.3=8.5.30-1ubuntu1.4=8.5.39-1ubuntu1~18.04.1=8.5.39-1ubuntu1~18.04.2=8.5.39-1ubuntu1~18.04.3=8.5.39-1ubuntu1~18.04.3+esm1=8.5.39-1ubuntu1~18.04.3+esm2=8.5.39-1ubuntu1~18.04.3+esm3=8.5.39-1ubuntu1~18.04.3+esm4=8.5.39-1ubuntu1~18.04.3+esm5=8.5.39-1ubuntu1~18.04.3+esm6
Ubuntu:Pro:18.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm8?arch=source&distro=esm-apps/bionic
Affected versions
<9.0.16-3ubuntu0.18.04.2+esm8=9.0.16-3~18.04.1=9.0.16-3ubuntu0.18.04.1=9.0.16-3ubuntu0.18.04.2=9.0.16-3ubuntu0.18.04.2+esm1=9.0.16-3ubuntu0.18.04.2+esm2=9.0.16-3ubuntu0.18.04.2+esm3=9.0.16-3ubuntu0.18.04.2+esm4=9.0.16-3ubuntu0.18.04.2+esm5=9.0.16-3ubuntu0.18.04.2+esm6=9.0.16-3ubuntu0.18.04.2+esm7
Ubuntu:Pro:20.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm3?arch=source&distro=esm-apps/focal
Affected versions
<9.0.31-1ubuntu0.9+esm3=9.0.24-1=9.0.27-1=9.0.31-1=9.0.31-1ubuntu0.1=9.0.31-1ubuntu0.2=9.0.31-1ubuntu0.3=9.0.31-1ubuntu0.4=9.0.31-1ubuntu0.5=9.0.31-1ubuntu0.6=9.0.31-1ubuntu0.7=9.0.31-1ubuntu0.8=9.0.31-1ubuntu0.9=9.0.31-1ubuntu0.9+esm1=9.0.31-1ubuntu0.9+esm2
Ubuntu:Pro:22.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-apps/jammy
Affected versions
<9.0.58-1ubuntu0.2+esm4=9.0.43-3=9.0.54-1=9.0.55-1=9.0.58-1=9.0.58-1ubuntu0.1=9.0.58-1ubuntu0.1+esm1=9.0.58-1ubuntu0.1+esm2=9.0.58-1ubuntu0.1+esm3=9.0.58-1ubuntu0.1+esm4=9.0.58-1ubuntu0.2=9.0.58-1ubuntu0.2+esm1=9.0.58-1ubuntu0.2+esm2=9.0.58-1ubuntu0.2+esm3
Ubuntu:Pro:24.04:LTSmore threats →ghsa
tomcat10
pkg:deb/ubuntu/[email protected]~esm4?arch=source&distro=esm-apps/noble
Affected versions
<10.1.16-1ubuntu0.1~esm4=10.1.10-1=10.1.14-1=10.1.15-1=10.1.16-1=10.1.16-1ubuntu0.1~esm1=10.1.16-1ubuntu0.1~esm2=10.1.16-1ubuntu0.1~esm3
Ubuntu:Pro:24.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm3?arch=source&distro=esm-apps/noble
Affected versions
<9.0.70-2ubuntu0.1+esm3=9.0.70-1ubuntu1=9.0.70-2=9.0.70-2ubuntu0.1=9.0.70-2ubuntu0.1+esm1=9.0.70-2ubuntu0.1+esm2
Ubuntu:25.10more threats →ghsa
tomcat10
pkg:deb/ubuntu/[email protected]?arch=source&distro=questing
Affected versions
<10.1.40-1ubuntu1.25.10.1=10.1.35-1=10.1.40-1=10.1.40-1ubuntu1
Ubuntu:25.10more threats →ghsa
tomcat11
pkg:deb/ubuntu/[email protected]?arch=source&distro=questing
Affected versions
=11.0.6-1
Ubuntu:25.10more threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]?arch=source&distro=questing
Affected versions
<9.0.95-1ubuntu1.1=9.0.70-2ubuntu1.1=9.0.70-2ubuntu2=9.0.70-2ubuntu3=9.0.95-1ubuntu1
Ubuntu:26.04:LTSmore threats →ghsa
tomcat10
pkg:deb/ubuntu/[email protected]?arch=source&distro=resolute
Affected versions
<10.1.40-1ubuntu1.26.04.1=10.1.40-1ubuntu1
Ubuntu:26.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]?arch=source&distro=resolute
Affected versions
<9.0.115-1ubuntu0.1=9.0.95-1ubuntu1=9.0.111-1=9.0.115-1
Ubuntu:26.04:LTSmore threats →ghsa
tomcat11
pkg:deb/ubuntu/[email protected]~26.04.1?arch=source&distro=resolute
Affected versions
=11.0.6-1=11.0.11-1=11.0.15-1=11.0.18-1=11.0.18-1ubuntu0.1~esm1=11.0.22-2ubuntu2~26.04.1

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 09/12/2026, 14:04:16 UTC

Technical Analysis

CVE-2026-43513 describes a vulnerability in Apache Tomcat's LockOutRealm where user names are treated as case-sensitive incorrectly. This improper handling of case sensitivity can be exploited by remote attackers to bypass account lockout protections and potentially access sensitive information. The issue affects a wide range of Apache Tomcat versions from 7.0.0 up to 11.0.21. The vulnerability has been addressed in Apache Tomcat releases 11.0.22, 10.1.55, and 9.0.118. Ubuntu security advisories confirm the existence of this vulnerability and provide fixed package versions. After applying updates, a Tomcat service restart is required to complete remediation.

Potential Impact

Remote attackers could exploit this vulnerability to bypass account lockout protections in Apache Tomcat's LockOutRealm, potentially allowing unauthorized access or information disclosure. This could weaken authentication controls and increase the risk of unauthorized access to sensitive data.

Mitigation Recommendations

A fix is available. Users should upgrade Apache Tomcat to versions 11.0.22, 10.1.55, or 9.0.118 or later as appropriate. After updating, restart the Tomcat service to apply the changes. Follow vendor advisories and standard system update procedures to obtain and apply these patches.

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Technical Details

Gcve Source
db.gcve.eu
Osv Id
UBUNTU-CVE-2026-43513
Osv Schema Version
1.7.0
Ecosystems
["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
Cvss Version
3.1
State
PUBLISHED

Threat ID: 6a58b4b668715ace43da9756

Added to database: 07/16/2026, 10:38:46 UTC

Last enriched: 09/12/2026, 14:04:16 UTC

Last updated: 09/14/2026, 22:01:34 UTC

Views: 35

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