CVE-2026-65637: Improper Input Validation vulnerability in Apache Tomcat due to incomplete fix for CVE-2026-32990. This iss

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-65637 is a critical-severity flaw (CVSS 9.8) affecting tomcat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper Input Validation vulnerability in Apache Tomcat due to incomplete fix for CVE-2026-32990. This issue affects Apache Tomcat: from 11.0.20 through 11.0.24, from 10.1.53 through 10.1.57, from 9.0.115 through 9.0.120. Users are recommended to upgrade to version 11.0.25, 10.1.58 or 9.0.121, which fix the issue.

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-20
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 15:19 UTCUpdated Record last modified

apache tomcat UPGRADE

Affected: >= 9.0.115 and < 9.0.121 · >= 10.1.53 and < 10.1.58 · >= 11.0.20 and < 11.0.25

Fixed in: 9.0.121, 10.1.58, 11.0.25

Safe to downgrade to: a release before 9.0.115

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 9.0.115 (Debian / Ubuntu)

apt-cache madison tomcat sudo apt install tomcat=<VERSION_BEFORE_9.0.115> 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_9.0.115> 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.

Exact fixes by distribution

Fedora ELN · rust-snpguest · FIXED · 0.11.0-1.eln159 · FEDORA-2026-baa01ba6c8 · source

sudo dnf upgrade --advisory=FEDORA-2026-baa01ba6c8

Fedora 46 · rust-sev · FIXED · 8.0.0-1.fc46 · FEDORA-2026-df06b5fb0c · source

sudo dnf upgrade --advisory=FEDORA-2026-df06b5fb0c

Debian 12 · tomcat10 · NO FIX YET

Debian 13 · tomcat10 · NO FIX YET

Debian 13 · tomcat11 · NO FIX YET

Debian 12 · tomcat9 · FIXED · 9.0.70-2

sudo apt update && sudo apt install --only-upgrade tomcat9 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' tomcat9)" ge "9.0.70-2" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · tomcat · NO FIX YET

RHEL 10 · tomcat9 · NO FIX YET

RHEL 6 · tomcat6 · DEFERRED

RHEL 7 · tomcat · DEFERRED

RHEL 8 · pki-deps:10.6/pki-servlet-engine · NOT AFFECTED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-3151 · source

sudo dnf update --advisory=ALAS2023-2026-3151

Advisories and coverage

Official advisories

Amazon Linux 2023 ALAS: ALAS2023-2026-3151 (important): tomcat11 2026-10-12

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-2026-65637?

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

Is CVE-2026-65637 being exploited?

CVE-2026-65637 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-2026-65637 affect?

CVE-2026-65637 affects tomcat. Severity is critical (CVSS 9.8). Improper Input Validation vulnerability in Apache Tomcat due to incomplete fix for CVE-2026-32990. This issue affects Apache Tomcat: from 11.0.20 through 11.0.24, from 10.1.53 through 10.1.57, from 9.0.115 through 9.0.120. Users are r

How urgent is CVE-2026-65637?

Priority 60/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache Tomcat vulnerabilities

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References

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