CVE-2023-42794 Apache Tomcat: FileUpload: DoS due to accumulation of temporary files on Windows
An attacker can cause a denial of service by filling the disk with temporary files on Windows due to incomplete cleanup of uploaded files.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-42794?
CVE-2023-42794 is a medium-severity denial of service vulnerability in Apache Tomcat, published on 10 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Incomplete Cleanup vulnerability in Apache Tomcat.
The internal fork of Commons FileUpload packaged with Apache Tomcat 9.0.70 through 9.0.80 and 8.5.85 through 8.5.93 included an unreleased, in progress refactoring that exposed a potential denial of service on Windows if a web application opened a stream for an uploaded file but failed to close the stream. The file would never be deleted from disk creating the possibility of an eventual denial of service due to the disk being full.
Other, EOL versions may also be affected.
Users are recommended to upgrade to version 9.0.81 onwards or 8.5.94 onwards, which fixes the issue.
Weakness: CWE-459
Which versions are affected by CVE-2023-42794?
5 open source packages ship an affected version, including org.apache.tomcat:tomcat-coyote and tomcat. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.apache.tomcat:tomcat-coyote Maven | From 8.5.85 | 8.5.94 |
org.apache.tomcat:tomcat-coyote Maven | From 8.5.85 | 8.5.94 |
org.apache.tomcat:tomcat-coyote Maven | From 9.0.70 | 9.0.81 |
org.apache.tomcat:tomcat-coyote Maven | From 9.0.70 | 9.0.81 |
tomcat Bitnami | From 8.5.85 | 8.5.94, 9.0.81 |
Products include Apache Tomcat.
How do I fix CVE-2023-42794?
Upgrade org.apache.tomcat:tomcat-coyote to a fixed version for your release line: 8.5.94 or 9.0.81.
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-2023-42794 being exploited?
There is no known exploitation of CVE-2023-42794 in the wild and no public exploit code.
Other vulnerabilities in Apache Tomcat
Sources
Also known as BIT-tomcat-2023-42794, CLSA-2025-1739387851, GHSA-jm7m-8jh6-29hp.