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Apache Tomcat CVE-2026-86248

| EUVDEUVD-2026-85234 CRITICAL
Improper Authentication (CWE-287)
2026-09-23 apache GHSA-c47j-g3rg-hrfq
Authentication Bypass Apache Java Red Hat Tomcat Suse Apache Tomcat Apache Software Foundation
Critical
Disputed · 9.8 Vendor: apache
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Severity by source

Sources disagree (Medium–Critical)
Vendor (apache) PRIMARY
9.8 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.4 HIGH

Network-reachable auth bypass (PR:N) but gated by non-default CLIENT_CERT config, disabled soft fail, and only 'some scenarios' (AC:H); bypassing auth exposes and lets an attacker act on protected resources (C:H/I:H).

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SUSE
9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Red Hat
5.9 MEDIUM
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: apache

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
Metadata Corrected
Sep 23, 2026 - 12:40 vuln.today
tag: Java added
Analysis Generated
Sep 23, 2026 - 12:18 vuln.today
CVE Published
Sep 23, 2026 - 11:29 cve.org
MEDIUM

DescriptionCVE.org

CLIENT_CERT authentication does not fail as expected for some scenarios when soft fail is disabled vulnerability in Apache Tomcat.

This issue affects Apache Tomcat: from 11.0.0-M14 through 11.0.25, from 10.1.22 through 10.1.59, from 9.0.92 through 9.0.121.

Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

Articles & Coverage 1

News Critical Authentication Bypass in Apache Tomcat - CVE-2026-86248 Sep 24, 2026

AnalysisAI

Authentication can succeed when it should have been rejected in Apache Tomcat deployments that use CLIENT_CERT (mutual-TLS) authentication with soft fail disabled, allowing network attackers to reach resources that the mutual-TLS configuration was meant to protect. The affected range is broad - 9.0.92 through 9.0.121, 10.1.22 through 10.1.59, and 11.0.0-M14 through 11.0.25 - but the flaw is gated on two non-default conditions (the CLIENT_CERT authenticator in use and soft fail turned off) and, per the vendor, only manifests in some scenarios, so it is not universally reproducible even on correctly configured vulnerable instances. …

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Vulnerability AssessmentAI

Exploitation Exploitation requires the Tomcat instance to be configured for CLIENT_CERT authentication (mutual-TLS / clientAuth with the CLIENT-CERT authentication method) AND to have soft fail disabled - both non-default configurations. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine authentication-integrity flaw in a ubiquitous product, but the real-world risk is moderate and gated by configuration rather than critical. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Upgrade to a fixed release: Apache Tomcat 11.0.26, 10.1.60, or 9.0.122, which the vendor states resolve the issue; these are vendor-released patches and should be validated against your application before rolling out, since minor-version jumps within the 9.0.x and 10.1.x lines can carry other behavior changes. … Detailed patch versions, workarounds, and compensating controls in full report.
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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise Module for Basesystem 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Fixed

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CVE-2026-86248 vulnerability details – vuln.today
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