---
id: CVE-2021-30640
title: >-
  A vulnerability in the JNDI Realm of Apache Tomcat allows an attacker to
  authenticate using variations of a valid user name and/or to bypass some of
  the protection provided by the LockOut Realm
summary: >-
  A vulnerability in the JNDI Realm of Apache Tomcat allows an attacker to
  authenticate using variations of a valid user name and/or to bypass some of
  the protection provided by the LockOut Realm. This issue affects Apache Tomcat
  10.0.0-M1…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'
cwe:
  - CWE-116
vendor: apache
product: tomcat
affected:
  - 'tomcat >= 7.0.0, < 7.0.109'
  - 'tomcat >= 8.5.0, < 8.5.66'
  - 'tomcat >= 9.0.0, < 9.0.46'
  - 'tomcat >= 10.0.0, < 10.0.6'
  - communications_cloud_native_core_policy = 1.14.0
  - 'communications_diameter_signaling_router >= 8.0.0, <= 8.5.0'
  - communications_pricing_design_center = 12.0.0.3.0
  - hospitality_cruise_shipboard_property_management_system = 20.1.0
  - 'tekelec_platform_distribution >= 7.4.0, <= 7.7.1'
  - debian_linux = 9.0
  - debian_linux = 10.0
  - debian_linux = 11.0
patched:
  - tomcat 10.0.6
published: '2021-07-12'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T21:17:35.173'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-30640'
references:
  - url: >-
      https://lists.apache.org/thread.html/r59f9ef03929d32120f91f4ea7e6e79edd5688d75d0a9b65fd26d1fe8%40%3Cannounce.tomcat.apache.org%3E
    label: security@apache.org
  - url: 'https://lists.debian.org/debian-lts-announce/2021/08/msg00009.html'
    label: security@apache.org
  - url: 'https://security.gentoo.org/glsa/202208-34'
    label: security@apache.org
  - url: 'https://security.netapp.com/advisory/ntap-20210827-0007/'
    label: security@apache.org
  - url: 'https://www.debian.org/security/2021/dsa-4952'
    label: security@apache.org
  - url: 'https://www.debian.org/security/2021/dsa-4986'
    label: security@apache.org
  - url: 'https://www.oracle.com//security-alerts/cpujul2021.html'
    label: security@apache.org
  - url: 'https://www.oracle.com/security-alerts/cpujan2022.html'
    label: security@apache.org
  - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html'
    label: security@apache.org
  - url: >-
      https://lists.apache.org/thread.html/r59f9ef03929d32120f91f4ea7e6e79edd5688d75d0a9b65fd26d1fe8%40%3Cannounce.tomcat.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2021/08/msg00009.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202208-34'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20210827-0007/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.debian.org/security/2021/dsa-4952'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.debian.org/security/2021/dsa-4986'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.oracle.com//security-alerts/cpujul2021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.oracle.com/security-alerts/cpujan2022.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.09886
epssPercentile: 0.95464
ingestedAt: '2026-10-08T22:11:53.737Z'
---

## Overview

A vulnerability in the JNDI Realm of Apache Tomcat allows an attacker to authenticate using variations of a valid user name and/or to bypass some of the protection provided by the LockOut Realm. This issue affects Apache Tomcat 10.0.0-M1 to 10.0.5; 9.0.0.M1 to 9.0.45; 8.5.0 to 8.5.65.

## Affected

- `tomcat >= 7.0.0, < 7.0.109`
- `tomcat >= 8.5.0, < 8.5.66`
- `tomcat >= 9.0.0, < 9.0.46`
- `tomcat >= 10.0.0, < 10.0.6`
- `communications_cloud_native_core_policy = 1.14.0`
- `communications_diameter_signaling_router >= 8.0.0, <= 8.5.0`
- `communications_pricing_design_center = 12.0.0.3.0`
- `hospitality_cruise_shipboard_property_management_system = 20.1.0`
- `tekelec_platform_distribution >= 7.4.0, <= 7.7.1`
- `debian_linux = 9.0`
- `debian_linux = 10.0`
- `debian_linux = 11.0`

## Remediation

Upgrade past the affected range:

- `tomcat 10.0.6`