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

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.

Published: 2026-05-12 Last update: 2026-05-15 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-43513 is rated Low Risk (36.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-43513

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-16 0.02% 0.06% +0.04%
2 2026-05-13 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-43513

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-43513

GitHub Security Advisory for CVE-2026-43513

GHSA-5mp6-jrq3-r938 · Severity: high · Ecosystem: maven — Apache Tomcat: LockOutRealm treats user names as case-sensitive

OS Trackers for CVE-2026-43513

vendor priority summary link
debian not yet assigned CVE-2026-43513 not yet assigned priority: Debian including 3 source packages (tomcat10, tomcat11, tomcat9), 12 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 12. https://security-tracker.debian.org/tracker/CVE-2026-43513
suse medium — https://www.suse.com/security/cve/CVE-2026-43513/
ubuntu medium CVE-2026-43513 medium priority: Ubuntu including 6 source packages (tomcat10, tomcat11, tomcat6, tomcat7, tomcat8, tomcat9), 37 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 15, needed 13, released 5, ignored 3, not-affected 1. https://ubuntu.com/security/CVE-2026-43513

Affected software / configurations for CVE-2026-43513

Vendor Product Version Raw CPE
apache tomcat >= 7.0.0, <= 7.0.109 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 8.5.0, <= 8.5.100 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 9.0.0, < 9.0.118 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 10.1.0, < 10.1.55 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 11.0.0, < 11.0.22 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*

References for CVE-2026-43513

cvelogic Threat Intelligence