CVE-2026-43513

Description

Improper Handling of Case Sensitivity vulnerability in LockOutRealm in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 10.1.0-M1 through 10.1.54, from 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
tomcat6	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	14.04 LTS trusty	Fixed 6.0.39-1ubuntu0.1+esm3
tomcat7	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	18.04 LTS bionic	Not affected
	14.04 LTS trusty	Fixed 7.0.52-1ubuntu0.16+esm2
tomcat8	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	18.04 LTS bionic	Vulnerable
	16.04 LTS xenial	Vulnerable
tomcat9	26.04 LTS resolute	Vulnerable
	25.10 questing	Vulnerable
	24.04 LTS noble	Vulnerable
	22.04 LTS jammy	Vulnerable
	20.04 LTS focal	Vulnerable
	18.04 LTS bionic	Vulnerable
tomcat10	26.04 LTS resolute	Vulnerable
	25.10 questing	Vulnerable
	24.04 LTS noble	Vulnerable
	22.04 LTS jammy	Not in release
tomcat11	26.04 LTS resolute	Vulnerable
	25.10 questing	Vulnerable
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release

Get expanded security coverage with Ubuntu Pro

Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use.

Get Ubuntu Pro 30-day free trial

Notes

ebarretto

xenial tomcat6 only builds libservlet2.5-java, not the Tomcat server binaries bionic tomcat7 only builds libservlet3.0-java, not the Tomcat server binaries

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
tomcat6	Upstream: 6dd75be
tomcat7	Upstream: 6dd75be

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	None
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

Related Ubuntu Security Notices (USN)

USN-8383-1
Tomcat vulnerabilities
4 June 2026