Is CVE-2026-79677 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-79677 being exploited in the wild.

How severe is CVE-2026-79677?

High severity, with a CVSS score of 7.5, published 23 September 2026.

Which products and versions are affected?

Apache Tomcat 11.0.0-M1 through 11.0.25, 10.1.0-M1 through 10.1.59, 9.0.0.M1 through 9.0.121, 8.5.0 through 8.5.100, 7.0.43 through 7.0.109.

Is there a fix for CVE-2026-79677?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-79677 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-79677?

Check whether you run Apache Tomcat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-79677: Apache Tomcat WebSocket denial of service due to lost async write timeout

CVE-2026-79677 · Severity: high · CVSS 7.5 · Published 2026-09-23

Apache Tomcat, a widely-used application server that runs Java web applications, has a vulnerability affecting WebSocket connections. An attacker can trigger a denial of service by causing the server to lose track of timeouts on asynchronous WebSocket write operations, allowing malicious writes to accumulate and exhaust server resources.

Technologies: Apache Tomcat. Vendors: Apache.

Quick answers

Is CVE-2026-79677 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-79677 being exploited in the wild.
How severe is CVE-2026-79677?: High severity, with a CVSS score of 7.5, published 23 September 2026.
Which products and versions are affected?: Apache Tomcat 11.0.0-M1 through 11.0.25, 10.1.0-M1 through 10.1.59, 9.0.0.M1 through 9.0.121, 8.5.0 through 8.5.100, 7.0.43 through 7.0.109.
Is there a fix for CVE-2026-79677?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-79677 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-79677?: Check whether you run Apache Tomcat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A missing resource cleanup and comparison using incorrect factors in Tomcat's WebSocket handling allows asynchronous write timeouts to be lost, leading to unbounded resource consumption. The vulnerability affects multiple supported and unsupported versions across the 7.x, 8.x, 9.x, 10.x, and 11.x branches. The attack can be triggered over the network via WebSocket connections without authentication or special preconditions.

Affected products

Apache Tomcat 11.0.0-M1 through 11.0.25, 10.1.0-M1 through 10.1.59, 9.0.0.M1 through 9.0.121, 8.5.0 through 8.5.100, 7.0.43 through 7.0.109

Timeline

2026-09-23: disclosed

References

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