What is CVE-2026-55955?

CVE-2026-55955 is a medium-severity vulnerability in Apache Tomcat, classified under Improper Authentication. CVSS score: 6.5/10. Published 2026-06-29.

How severe is CVE-2026-55955?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Auth bypass in Apache Tomcat

CVE-2026-55955

Improper Authentication vulnerability in Apache Tomcat allowed a replay attack against the EncryptionInterceptor in the cluster component. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.22, from 10.1.0-M1 through 10.1.55, from 9.0.13 through 9.0.18, from 8.5.38 through 8.5.100, from 7.0.100 through 7.0.109. Users are recommended to upgrade to version 11.0.23, 10.1.56, 9.0.119, which fixes the issue.

Vulnerability class: Broken Authentication

Published 2026-06-29 · last modified 2026-07-10.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.004 (35.4th percentile), scored 2026-09-29.

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: 0.004 · newest: 0.004 · change: 0.000

Affected products

Apache Tomcat
Apache Software Foundation Tomcat — versions 11.0.0-M1, 10.1.0-M1, 9.0.13

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

lists.apache.org/thread/g4p5sf45p3f9r011pwqs9r54yd64s106 (vendor-advisory, Mailing List, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)

Frequently asked questions

What is CVE-2026-55955?: CVE-2026-55955 is a medium-severity vulnerability in Apache Tomcat, classified under Improper Authentication. CVSS score: 6.5/10. Published 2026-06-29.
How severe is CVE-2026-55955?: Medium severity. CVSS v3 base score is 6.5 out of 10.