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

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-10-10 · updated 2026-10-08
Weakness: CWE-459

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.

Affected products

Apache Tomcat: from 8.5.85 before 8.5.94; from 9.0.70 before 9.0.81 — fixed in 8.5.94, 9.0.81

How to fix

Upgrade to a fixed version: Apache Tomcat 8.5.94, 9.0.81. Check the vendor advisory for mitigations.

References

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