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EPSS 0.5%top 62%

Tomcat6: Improper Authentication vulnerability in Apache Tomcat allowed a replay attack against the EncryptionInterceptor in the cluster component.

0
Medium
VulnerabilityCVE-2026-55955gcveosvubuntu-cve-2026-55955ubuntu-pro-14-04-ltsubuntu-pro-16-04-ltsubuntu-pro-18-04-ltsubuntu-pro-20-04-ltsubuntu-pro-22-04-ltsubuntu-pro-24-04-ltsubuntu-25-10ubuntu-26-04-ltsubuntu-24-04-lts
Published: 06/29/2026 (06/29/2026, 21:16:00 UTC)
Source: GCVE Database
Product: tomcat6

Description

An improper authentication vulnerability in Apache Tomcat's cluster component allows a replay attack against the EncryptionInterceptor. This affects multiple versions of Apache Tomcat from 7.0.100 through 7.0.109, 8.5.38 through 8.5.100, 9.0.13 through 9.0.18, 10.1.0-M1 through 10.1.55, and 11.0.0-M1 through 11.0.22. The issue is resolved in versions 11.0.23, 10.1.56, and 9.0.119. Users should upgrade to these fixed versions to mitigate the vulnerability.

CVSS v3.1

Score 6.5medium

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected software

Ubuntu:Pro:14.04:LTSmore threats →ghsa
tomcat6
pkg:deb/ubuntu/[email protected]+esm3?arch=source&distro=esm-infra-legacy/trusty
Affected versions
=6.0.37-1=6.0.39-1=6.0.39-1ubuntu0.1=6.0.39-1ubuntu0.1+esm1=6.0.39-1ubuntu0.1+esm2=6.0.39-1ubuntu0.1+esm3
Ubuntu:Pro:14.04:LTSmore threats →ghsa
tomcat7
pkg:deb/ubuntu/[email protected]+esm2?arch=source&distro=esm-infra-legacy/trusty
Affected versions
=7.0.42-1=7.0.47-1=7.0.50-1=7.0.52-1=7.0.52-1ubuntu0.1=7.0.52-1ubuntu0.3=7.0.52-1ubuntu0.6=7.0.52-1ubuntu0.7=7.0.52-1ubuntu0.8=7.0.52-1ubuntu0.9=7.0.52-1ubuntu0.10=7.0.52-1ubuntu0.11=7.0.52-1ubuntu0.13=7.0.52-1ubuntu0.14=7.0.52-1ubuntu0.15=7.0.52-1ubuntu0.16=7.0.52-1ubuntu0.16+esm1=7.0.52-1ubuntu0.16+esm2
Ubuntu:Pro:16.04:LTSmore threats →ghsa
tomcat8
pkg:deb/ubuntu/[email protected]+esm2?arch=source&distro=esm-infra-legacy/xenial
Affected versions
=8.0.26-1=8.0.28-1=8.0.30-1=8.0.32-1=8.0.32-1ubuntu1=8.0.32-1ubuntu1.1=8.0.32-1ubuntu1.2=8.0.32-1ubuntu1.3=8.0.32-1ubuntu1.4=8.0.32-1ubuntu1.5=8.0.32-1ubuntu1.6=8.0.32-1ubuntu1.7=8.0.32-1ubuntu1.8=8.0.32-1ubuntu1.9=8.0.32-1ubuntu1.10=8.0.32-1ubuntu1.11=8.0.32-1ubuntu1.13=8.0.32-1ubuntu1.13+esm1=8.0.32-1ubuntu1.13+esm2
Ubuntu:Pro:16.04:LTSmore threats →ghsa
tomcat7
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-apps-legacy/xenial
Affected versions
=7.0.64-1=7.0.68-1=7.0.68-1ubuntu0.1=7.0.68-1ubuntu0.3=7.0.68-1ubuntu0.4=7.0.68-1ubuntu0.4+esm1=7.0.68-1ubuntu0.4+esm2=7.0.68-1ubuntu0.4+esm3=7.0.68-1ubuntu0.4+esm4
Ubuntu:Pro:18.04:LTSmore threats →ghsa
tomcat8
pkg:deb/ubuntu/[email protected]~18.04.3+esm6?arch=source&distro=esm-apps/bionic
Affected versions
=8.5.21-1ubuntu1=8.5.29-1=8.5.30-1=8.5.30-1ubuntu1=8.5.30-1ubuntu1.2=8.5.30-1ubuntu1.3=8.5.30-1ubuntu1.4=8.5.39-1ubuntu1~18.04.1=8.5.39-1ubuntu1~18.04.2=8.5.39-1ubuntu1~18.04.3=8.5.39-1ubuntu1~18.04.3+esm1=8.5.39-1ubuntu1~18.04.3+esm2=8.5.39-1ubuntu1~18.04.3+esm3=8.5.39-1ubuntu1~18.04.3+esm4=8.5.39-1ubuntu1~18.04.3+esm5=8.5.39-1ubuntu1~18.04.3+esm6
Ubuntu:Pro:18.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm8?arch=source&distro=esm-apps/bionic
Affected versions
=9.0.16-3~18.04.1=9.0.16-3ubuntu0.18.04.1=9.0.16-3ubuntu0.18.04.2=9.0.16-3ubuntu0.18.04.2+esm1=9.0.16-3ubuntu0.18.04.2+esm2=9.0.16-3ubuntu0.18.04.2+esm3=9.0.16-3ubuntu0.18.04.2+esm4=9.0.16-3ubuntu0.18.04.2+esm5=9.0.16-3ubuntu0.18.04.2+esm6=9.0.16-3ubuntu0.18.04.2+esm7=9.0.16-3ubuntu0.18.04.2+esm8
Ubuntu:Pro:20.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm3?arch=source&distro=esm-apps/focal
Affected versions
=9.0.24-1=9.0.27-1=9.0.31-1=9.0.31-1ubuntu0.1=9.0.31-1ubuntu0.2=9.0.31-1ubuntu0.3=9.0.31-1ubuntu0.4=9.0.31-1ubuntu0.5=9.0.31-1ubuntu0.6=9.0.31-1ubuntu0.7=9.0.31-1ubuntu0.8=9.0.31-1ubuntu0.9=9.0.31-1ubuntu0.9+esm1=9.0.31-1ubuntu0.9+esm2=9.0.31-1ubuntu0.9+esm3
Ubuntu:Pro:22.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-apps/jammy
Affected versions
=9.0.43-3=9.0.54-1=9.0.55-1=9.0.58-1=9.0.58-1ubuntu0.1=9.0.58-1ubuntu0.1+esm1=9.0.58-1ubuntu0.1+esm2=9.0.58-1ubuntu0.1+esm3=9.0.58-1ubuntu0.1+esm4=9.0.58-1ubuntu0.2=9.0.58-1ubuntu0.2+esm1=9.0.58-1ubuntu0.2+esm2=9.0.58-1ubuntu0.2+esm3=9.0.58-1ubuntu0.2+esm4
Ubuntu:Pro:24.04:LTSmore threats →ghsa
tomcat10
pkg:deb/ubuntu/[email protected]~esm4?arch=source&distro=esm-apps/noble
Affected versions
=10.1.10-1=10.1.14-1=10.1.15-1=10.1.16-1=10.1.16-1ubuntu0.1~esm1=10.1.16-1ubuntu0.1~esm2=10.1.16-1ubuntu0.1~esm3=10.1.16-1ubuntu0.1~esm4
Ubuntu:Pro:24.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]+esm3?arch=source&distro=esm-apps/noble
Affected versions
=9.0.70-1ubuntu1=9.0.70-2=9.0.70-2ubuntu0.1=9.0.70-2ubuntu0.1+esm1=9.0.70-2ubuntu0.1+esm2=9.0.70-2ubuntu0.1+esm3
Ubuntu:25.10more threats →ghsa
tomcat10
pkg:deb/ubuntu/[email protected]?arch=source&distro=questing
Affected versions
=10.1.35-1=10.1.40-1=10.1.40-1ubuntu1=10.1.40-1ubuntu1.25.10.1
Ubuntu:25.10more threats →ghsa
tomcat11
pkg:deb/ubuntu/[email protected]?arch=source&distro=questing
Affected versions
=11.0.6-1
Ubuntu:25.10more threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]?arch=source&distro=questing
Affected versions
=9.0.70-2ubuntu1.1=9.0.70-2ubuntu2=9.0.70-2ubuntu3=9.0.95-1ubuntu1=9.0.95-1ubuntu1.1
Ubuntu:26.04:LTSmore threats →ghsa
tomcat10
pkg:deb/ubuntu/[email protected]~26.04.1?arch=source&distro=resolute
Affected versions
=10.1.40-1ubuntu1=10.1.40-1ubuntu1.26.04.1=10.1.55-1ubuntu2~26.04.1
Ubuntu:26.04:LTSmore threats →ghsa
tomcat9
pkg:deb/ubuntu/[email protected]~26.04.1?arch=source&distro=resolute
Affected versions
=9.0.95-1ubuntu1=9.0.111-1=9.0.115-1=9.0.115-1ubuntu0.1=9.0.118-1~26.04.1
Ubuntu:26.04:LTSmore threats →ghsa
tomcat11
pkg:deb/ubuntu/[email protected]~26.04.1?arch=source&distro=resolute
Affected versions
=11.0.6-1=11.0.11-1=11.0.15-1=11.0.18-1=11.0.18-1ubuntu0.1~esm1=11.0.22-2ubuntu2~26.04.1

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 07/30/2026, 11:18:52 UTC

Technical Analysis

Apache Tomcat contains an improper authentication vulnerability in the cluster component's EncryptionInterceptor, which permits a replay attack. This vulnerability affects a range of versions including 7.0.100 to 7.0.109, 8.5.38 to 8.5.100, 9.0.13 to 9.0.18, 10.1.0-M1 to 10.1.55, and 11.0.0-M1 to 11.0.22. The vulnerability is addressed by upgrading to fixed versions 11.0.23, 10.1.56, and 9.0.119. The vulnerability has a CVSS 3.1 vector indicating network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, and low confidentiality and integrity impacts, with no availability impact.

Potential Impact

The vulnerability allows an attacker to perform a replay attack against the EncryptionInterceptor in the cluster component of Apache Tomcat, potentially compromising confidentiality and integrity of communications within the cluster. There is no impact on availability. The CVSS 3.1 vector indicates a medium severity with low confidentiality and integrity impacts.

Mitigation Recommendations

A fix is available. Users are recommended to upgrade Apache Tomcat to versions 11.0.23, 10.1.56, or 9.0.119 or later, which address this vulnerability. No other mitigation steps are indicated by the vendor advisory.

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Technical Details

Gcve Source
db.gcve.eu
Osv Id
UBUNTU-CVE-2026-55955
Osv Schema Version
1.7.0
Aliases
[]
Ecosystems
["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
Database Specific Severity
null
Cvss Version
3.1

Threat ID: 6a58b47468715ace43d8d70f

Added to database: 07/16/2026, 10:37:40 UTC

Last enriched: 07/30/2026, 11:18:52 UTC

Last updated: 07/31/2026, 19:24:48 UTC

Views: 8

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