What is CVE-2026-86248?

CVE-2026-86248 is a critical-severity vulnerability in Apache Software Foundation Tomcat, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-09-23.

How severe is CVE-2026-86248?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Apache Software Foundation Tomcat

CVE-2026-86248

CLIENT_CERT authentication does not fail as expected for some scenarios when soft fail is disabled vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M14 through 11.0.25, from 10.1.22 through 10.1.59, from 9.0.92 through 9.0.121. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

Vulnerability class: Broken Authentication

Published 2026-09-23 · last modified 2026-09-23.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Apache Software Foundation Tomcat

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

lists.apache.org/thread/nmkmjp9l53y8h3oc4n8fc0bkw9dv15sk (vendor-advisory)

Frequently asked questions

What is CVE-2026-86248?: CVE-2026-86248 is a critical-severity vulnerability in Apache Software Foundation Tomcat, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-09-23.
How severe is CVE-2026-86248?: Critical severity. CVSS v3 base score is 9.8 out of 10.