CVE-2026-55957: Missing Critical Step in Authentication vulnerability in Apache Tomcat when the JNDIRealm was configured to au

This week

HIGH 7.3REMOTEWATCHLISTUPGRADE

CVE-2026-55957 is a high-severity flaw (CVSS 7.3) affecting tomcat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Missing Critical Step in Authentication vulnerability in Apache Tomcat when the JNDIRealm was configured to authenticate binds using GSSAPI allowed attackers to authenticate without provided the correct password. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.4, from 10.1.0-M1 through 10.1.36, from 9.0.0.M1 through 9.0.100, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Users are recommended to upgrade to version 11.0.5,

Why this priority

High 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	7.3 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.9% (top 13%)
CISA exploited list	No
Weakness	CWE-304
Published	2026-06-29
Last modified	2026-10-25

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

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-29 21:16 UTCPublished CVE record published
2026-10-25 21:10 UTCUpdated Record last modified

apache tomcat UPGRADE

Affected: < 9.0.101 · >= 10.1.0 and < 10.1.37 · >= 11.0.0 and < 11.0.5

Fixed in: 9.0.101, 10.1.37, 11.0.5

Safe to downgrade to: a release before 10.1.0

1. Check installed version

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

2. UPGRADE to 9.0.101 (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 10.1.0 (Debian / Ubuntu)

apt-cache madison tomcat sudo apt install tomcat=<VERSION_BEFORE_10.1.0> 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_10.1.0> 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 46 · mingw-qt5-qtwebkit · FIXED · 5.212.0-0.46.alpha4.fc46 · FEDORA-2026-46ae541c22 · source

sudo dnf upgrade --advisory=FEDORA-2026-46ae541c22

Fedora ELN · kdominate · FIXED · 26.08.2-2.eln159 · FEDORA-2026-b1d98239fd · source

sudo dnf upgrade --advisory=FEDORA-2026-b1d98239fd

Debian 12 · tomcat10 · FIXED · 10.1.52-1~deb12u1

sudo apt update && sudo apt install --only-upgrade tomcat10 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' tomcat10)" ge "10.1.52-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · tomcat10 · FIXED · 10.1.52-1~deb13u1

sudo apt update && sudo apt install --only-upgrade tomcat10 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' tomcat10)" ge "10.1.52-1~deb13u1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · tomcat11 · FIXED · 11.0.15-1~deb13u1

sudo apt update && sudo apt install --only-upgrade tomcat11 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' tomcat11)" ge "11.0.15-1~deb13u1" && echo PATCHED || echo STILL-VULNERABLE

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 · tomcat9 · FIXED · tomcat9-9.0.110-2.el10_2

sudo dnf upgrade --advisory=RHSA-2026:18536 rpm -q tomcat9

RHEL 10 · tomcat · FIXED · tomcat-10.1.49-1.el10

sudo dnf upgrade --advisory=RHSA-2026:18537 rpm -q tomcat

RHEL 10.0 Extended Update Support · tomcat9 · FIXED · tomcat9-9.0.120-1.el10_0

sudo dnf upgrade --advisory=RHSA-2026:67163 rpm -q tomcat9

RHEL 10.0 Extended Update Support · tomcat · FIXED · tomcat-10.1.49-1.el10_0

sudo dnf upgrade --advisory=RHSA-2026:67164 rpm -q tomcat

RHEL 8 · tomcat · FIXED · tomcat-9.0.120-1.el8_10

sudo dnf upgrade --advisory=RHSA-2026:68677 rpm -q tomcat

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2025-911 · source

sudo dnf update --advisory=ALAS2023-2025-911

Amazon Linux 2 · see advisory · FIXED · ALAS2-2026-3864 · source

sudo yum update --advisory=ALAS2-2026-3864

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: mdvpat/CVE-2026-55957-PoC (0 stars)

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-2026-55957?

tomcat: upgrade to 9.0.101, 10.1.37, 11.0.5. Exact commands for each OS are on this page.

Is CVE-2026-55957 being exploited?

CVE-2026-55957 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-2026-55957 affect?

CVE-2026-55957 affects tomcat. Severity is high (CVSS 7.3). Missing Critical Step in Authentication vulnerability in Apache Tomcat when the JNDIRealm was configured to authenticate binds using GSSAPI allowed attackers to authenticate without provided the correct password. This issue affects Apache

How urgent is CVE-2026-55957?

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

Software pages

Apache Tomcat vulnerabilities

Related CVEs

CVE-2026-43512 CRITICAL 9.8 UPGRADE DEPRECATED: Authentication Bypass Issues vulnerability in digest authentication in Apache Tomcat. This issue
CVE-2026-53434 CRITICAL 9.1 UPGRADE Detection of Error Condition Without Action vulnerability in Apache Tomcat when configuring CRLs for a FFM bas
CVE-2026-55276 CRITICAL 9.1 UPGRADE Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty
CVE-2026-50229 MEDIUM 6.1 UPGRADE Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in the number gues
CVE-2026-53404 HIGH 7.3 UPGRADE Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat's rewrite valve meant that if the

References

← Back to latest CVEs