Allocation of Resources Without Limits or Throttling in Apache Tomcat - CVE-2026-66299
Published: July 28, 2026 / Updated: July 28, 2026
Vulnerability identifier: #VU139938
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-66299
CWE-ID: CWE-770
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Apache Foundation
Affected software:
Apache Tomcat
Apache Tomcat
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper resource management in the WebSocket chat example when buffering undelivered messages for a maliciously slow client connection. A remote attacker can maintain a slow client connection to cause a denial of service.
Only deployments exposing the example web application are vulnerable.
How to mitigate CVE-2026-66299
Install security update from vendor's website.