Auth bypass in Apache Tomcat
CVE-2026-66422
Improper Authorization vulnerability in Apache Tomcat cause by security-role-ref definitions being incorrectly used as role aliases within the Realm in additional to the correct usage with Request.isUserInRole(). This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.24, from 10.1.0-M1 through 10.1.57, from 9.0.25 through 9.0.120. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.46 through 8.5.100, from 7.0.97 through 7.0.109. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.25, 10.1.58 or 9.0.121, which fix the issue.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (35.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.004 · change: -0.001
Affected products
Weakness classification (CWE)
References
- lists.apache.org/thread/j5plylz1b2vhqvbkqn7k58nygxhcpk73 (vendor-advisory, Mailing List, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-66422?
- CVE-2026-66422 is a high-severity vulnerability in Apache Tomcat, classified under Improper Authorization. CVSS score: 8.1/10. Published 2026-08-25.
- How severe is CVE-2026-66422?
- High severity. CVSS v3 base score is 8.1 out of 10.