CVE-2026-66299

⚠️ high

Summary

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.

CVSS Score

7.5

High

EPSS Score

0.5

Exploit Probability

Published Date

2026-07-28

First Seen: 2026-07-31

📊 Relative Risk Intelligence

This CVE is Moderate Risk - more severe than 68.2% of all 344,912 vulnerabilities in our database.

#109,851

Above average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: Jul 28, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

YES

Can be exploited automatically

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

4ra1n, pyn3rd and unam4

SSVC data provided by CISA

Last Modified 2026-08-05

Source NVD 🔗

CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE IDs (Weakness Types)

CWE-400

📦 Affected Products 4

Vendor	Product	Status	Affected Versions
apache	tomcat	Affected	> 10.1.24 < 10.1.58
apache	tomcat	Affected	> 11.0.1 < 11.0.25
apache	tomcat	Affected	> 9.0.89 < 9.0.121
apache	tomcat	Affected	v11.0.0

🔗 References 2

https://lists.apache.org/thread/8owczcc1o8qw1rxmg9gv...

Mailing List Vendor Advisory

http://www.openwall.com/lists/oss-security/2026/07/2...

Mailing List Third Party Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-59083	⛔ critical	9.1	0.4	Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constra...	2026-07-14
CVE-2026-59084	⛔ critical	9.1	0.4	Insufficient Technical Documentation vulnerability in Apache Tomcat since the requirements to securely configure the Enc...	2026-07-14
CVE-2026-50229	🔶 medium	6.1	0.4	Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in the number guess example ...	2026-06-29
CVE-2026-53404	⚠️ high	7.3	0.4	Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat's rewrite valve meant that if the first cond...	2026-06-29
CVE-2026-53434	⛔ critical	9.1	0.4	Detection of Error Condition Without Action vulnerability in Apache Tomcat when configuring CRLs for a FFM based connect...	2026-06-29
CVE-2026-55276	⛔ critical	9.1	0.4	Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty authorisa...	2026-06-29

These CVEs affect the same products