CVE-2026-79677 Apache Tomcat: WebSocket DoS due to lost asynchronous write timeout
Apache Tomcat suffers from a denial of service vulnerability due to lost asynchronous write timeouts in WebSocket connections.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-79677?
CVE-2026-79677 is a high-severity denial of service vulnerability in Apache Tomcat, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-79677?
1 open source package ship an affected version, including tomcat.
| Package | Affected | Fixed in |
|---|---|---|
tomcat Bitnami | All versions | 9.0.45, 10.1.60, 11.0.26, 9.0.122 |
How do I fix CVE-2026-79677?
Upgrade tomcat to a fixed version for your release line: 9.0.45, 10.1.60, 11.0.26 or 9.0.122.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-79677 being exploited?
There is no known exploitation of CVE-2026-79677 in the wild and no public exploit code.
Sources
Also known as BIT-tomcat-2026-79677, DEBIAN-CVE-2026-79677, GHSA-r5gx-4gq8-822g, MINI-hgpm-j82r-g9xf, MINI-m754-5mr9-hfvh, MINI-mppw-6c2q-x35h and 1 more.