---
id: CVE-2026-86247
title: >-
  Race condition within a thread vulnerability in Apache Tomcat Native allowed
  client certificate verification requirements to be down-graded for some
  configurations.




  This issue affects Apache Tomcat Native: from 2.0.0 through 2.0.15, f…
summary: >-
  Race condition within a thread vulnerability in Apache Tomcat Native allowed
  client certificate verification requirements to be down-graded for some
  configurations.




  This issue affects Apache Tomcat Native: from 2.0.0 through 2.0.15, f…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-366
vendor: apache
product: tomcat_native
affected:
  - 'tomcat_native >= 1.3.0, < 1.3.9'
  - 'tomcat_native >= 2.0.0, < 2.0.16'
patched:
  - tomcat_native 2.0.16
published: '2026-09-23'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T13:46:49.633'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86247'
references:
  - url: 'https://lists.apache.org/thread/obsson6zhvfg0wsp2bx602l61ltj87r1'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/23/33'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-86247.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-86247'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2539393'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-86247'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86247'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00202
epssPercentile: 0.10005
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-23T15:30:32.467469Z'
scores:
  nvd: 7.4
  vendor: 4.8
ingestedAt: '2026-09-23T13:24:43.399Z'
---

## Overview

Race condition within a thread vulnerability in Apache Tomcat Native allowed client certificate verification requirements to be down-graded for some configurations.



This issue affects Apache Tomcat Native: from 2.0.0 through 2.0.15, from 1.3.0 through 1.3.8. Unsupported versions may also be affected.



Users are recommended to upgrade to version 2.0.16 or 1.3.9, which fixes the issue.

## Affected

- `tomcat_native >= 1.3.0, < 1.3.9`
- `tomcat_native >= 2.0.0, < 2.0.16`

## Remediation

Upgrade past the affected range:

- `tomcat_native 2.0.16`

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat JBoss Web Server 5, Red Hat JBoss Web Server 6, Red Hat JBoss Web Server 7 · no fix planned: Red Hat JBoss Web Server 5, Red Hat JBoss Web Server 6, Red Hat JBoss Web Server 7 · updated 2026-10-01 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-86247.json)