CVE-2023-42794 — tomcat-coyote
MEDIUMCVE-2023-42794 is a medium-severity (CVSS 5.9) CWE-459 vulnerability in org.apache.tomcat:tomcat-coyote. A fix is available for org.apache.tomcat:tomcat-coyote — see the affected versions and patch details below.
Apache Tomcat: FileUpload: DoS due to accumulation of temporary files on Windows
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-42794 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat-coyoteReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 9.0.70&&< 9.0.81 | 9.0.81org.apache.tomcat:tomcat-coyote:9.0.81 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 8.5.85&&< 8.5.94 | 8.5.94org.apache.tomcat:tomcat-coyote:8.5.94 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat:tomcat-coyote, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.tomcat:tomcat-coyote to 9.0.81 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-42794 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-42794 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-42794. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat rates this flaw as a Moderate impact as this would depend on how much information an attacker has over the environment (version and disk for example, increasing the Attack Complexity) as there is no guarantee the attack is successful. This may affect only scenarios where running an application on Windows.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | tomcat-1:9.0.62-27.el8_9.2 | RHSA-2024:0125 |
| Red Hat Enterprise Linux 9 | tomcat-1:9.0.62-37.el9_3.1 | RHSA-2024:0474 |
| Red Hat Fuse 7.12.1 | tomcat | RHSA-2023:7247 |
| Red Hat JBoss Web Server 5 | see advisory | RHSA-2023:7623 |
Frequently Asked Questions
Is CVE-2023-42794 in your dependencies?
O3 Security finds CVE-2023-42794 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.