CVE-2026-77791

Apache Tomcat: DoS via busy wait during WebSocket close

Published: Sep 23, 2026Updated: Sep 23, 2026 Sources: CVE List NVDCWE-400

7.5HIGH

Description

Uncontrolled Resource Consumption vulnerability in Apache Tomcat during sending of WebSocket close message enabled a DoS attack. This issue affects Apache Tomcat: from 11.0.0-M5 through 11.0.25, from 10.1.8 through 10.1.59, from 9.0.74 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.88 through 8.5.100. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:HAvailability

High

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Weaknesses

CWE-400

Affected Products

Apache Software Foundation

oss-project·USaka apache foundation

Apache TomcatOn-premWeb App

Networking Infrastructure / load-balancer-proxy

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique

Impact

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References

https://lists.apache.org/thread/mb1pjjooqytrl6hbvbt3rw1lqwlon4cz

lists.apache.org

http://www.openwall.com/lists/oss-security/2026/09/23/24

openwall.com

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