Vulnerability Database

374,644

Total vulnerabilities in the database

CVE-2026-66299 — apache / tomcat

Uncontrolled Resource Consumption

Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example.

This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue.

Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue.

  • Published: Jul 28, 2026
  • Updated: Jul 29, 2026
  • CVE: CVE-2026-66299
  • Severity: High
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: High
  • Score: 7.5
  • AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWEs:

Software From Fixed in
apache / tomcat 9.0.89 9.0.121
apache / tomcat 10.1.24 10.1.58
apache / tomcat 11.0.1 11.0.25
apache / tomcat 11.0.0-milestone20 11.0.0-milestone20.x
apache / tomcat 11.0.0-milestone21 11.0.0-milestone21.x
apache / tomcat 11.0.0-milestone22 11.0.0-milestone22.x
apache / tomcat 11.0.0-milestone23 11.0.0-milestone23.x
apache / tomcat 11.0.0-milestone24 11.0.0-milestone24.x
apache / tomcat 11.0.0-milestone25 11.0.0-milestone25.x
apache / tomcat 11.0.0-milestone26 11.0.0-milestone26.x

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.