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CVE-2026-79677: Apache Tomcat: WebSocket DoS due to lost asynchronous write timeout

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-23 · updated 2026-09-23
• Weakness: CWE-772

Description

Missing release of resource after effective lifetime, Comparison using wrong factors vulnerability in Apache Tomcat allows a denial of service as a result of lost time outs for asynchronous WebSocket writes. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.0.M1 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.0 through 8.5.100, from 7.0.43 through 7.0.109. 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.

Affected products

• Apache Tomcat: from 11.0.0-M1 through 11.0.25; from 10.1.0-M1 through 10.1.59; from 9.0.0.M1 through 9.0.121; from 8.5.0 through 8.5.100; from 7.0.43 through 7.0.109

References

• https://lists.apache.org/thread/bzwps6ck4szf2hmksbbon3syyl9qnkv8
• http://www.openwall.com/lists/oss-security/2026/09/23/27

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