CVE-2026-66422: Improper Authorization vulnerability in Apache Tomcat cause by security-role-ref definitions being incorrectly

This month

HIGH 8.1WATCHLISTUPGRADE

CVE-2026-66422 is a high-severity flaw (CVSS 8.1) affecting tomcat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 63%)
CISA exploited list	No
Weakness	CWE-285
Published	2026-08-25
Last modified	2026-08-27

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-08-27 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-25 22:17 UTCPublished CVE record published
2026-08-27 15:16 UTCUpdated Record last modified

apache tomcat UPGRADE

Affected: >= 7.0.97 and <= 7.0.109 · >= 8.5.46 and < 9.0.121 · >= 10.1.0 and < 10.1.58 · >= 11.0.0 and < 11.0.25

Fixed in: 9.0.121, 10.1.58, 11.0.25

Safe to downgrade to: a release before 7.0.97

1. Check installed version

apt-cache policy tomcat || rpm -q tomcat || tomcat --version

2. UPGRADE to 9.0.121 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade tomcat

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade tomcat

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 7.0.97 (Debian / Ubuntu)

apt-cache madison tomcat sudo apt install tomcat=<VERSION_BEFORE_7.0.97> sudo apt-mark hold tomcat

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list tomcat sudo dnf downgrade tomcat-<VERSION_BEFORE_7.0.97> sudo dnf versionlock add tomcat

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-66422?

tomcat: upgrade to 9.0.121, 10.1.58, 11.0.25. Exact commands for each OS are on this page.

Is CVE-2026-66422 being exploited?

CVE-2026-66422 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-66422 affect?

CVE-2026-66422 affects tomcat. Severity is high (CVSS 8.1). 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 Apach

How urgent is CVE-2026-66422?

Priority 43/100. High severity; On your watchlist

Software pages

Apache Tomcat vulnerabilities

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References

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