An incomplete cleanup vulnerability exists in Apache Tomcat, specifically in the internal fork of Commons FileUpload. This vulnerability affects versions 9.0.70 through 9.0.80 and 8.5.85 through 8.5.93. It exposes a potential denial of service on Windows systems if a web application opens a stream for an uploaded file but fails to close the stream. Consequently, the uploaded file remains on disk, leading to the risk of the disk becoming full and causing a denial of service.
The severity level of this vulnerability is medium, with a CVSS score of 5.9. This necessitates attention from organizations utilizing the affected versions of Apache Tomcat. The risk to organizations includes potential service disruption and operational inefficiencies resulting from a full disk.
Organizations should prioritize patching immediately to mitigate this risk. Users are recommended to upgrade to version 9.0.81 or 8.5.94 and above, which resolves this issue. Failure to address this vulnerability could expose organizations to significant operational challenges.
Other end-of-life versions may also be affected, thus reinforcing the importance of maintaining updated systems.
Vulnerability Details
The incomplete cleanup vulnerability in Apache Tomcat results from an unreleased, in-progress refactoring of the Commons FileUpload component. This vulnerability falls under the CWE classification of CWE-459, indicating the insufficient cleanup of temporary files. The vulnerability's CVSS vector indicates it has a network attack vector, high attack complexity, and requires no privileges or user interaction.
Technical Analysis
The root cause of this vulnerability is linked to the design and implementation of the file upload feature within Apache Tomcat. When a web application uploads a file and neglects to close the input stream, the temporary file remains on disk. This can lead to significant availability impacts, as the accumulation of unclosed streams can eventually fill the disk space.
The attack vector is network-based, meaning that an attacker could exploit the vulnerability by uploading files via a web application. The complexity of the attack is high, requiring specific conditions to be met for successful exploitation. The vulnerability does not require any privileges or user interaction, making it easier for attackers to leverage if the conditions are met.
Risk & Impact Analysis
Real-world deployment of this vulnerability poses significant risks to organizations. If left unaddressed, the accumulation of temporary files due to unclosed streams can lead to a denial of service, impacting critical services hosted on Apache Tomcat. The blast radius for this vulnerability can be substantial, especially in environments where multiple web applications rely on the affected versions.
Organizations should assess their exposure to this vulnerability based on their use of Apache Tomcat. The urgency of addressing this issue is highlighted by its medium CVSS score, which indicates that while it is not critical, it still requires prompt attention.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of Apache Tomcat are affected by this vulnerability: 9.0.70 through 9.0.80 and 8.5.85 through 8.5.93. Users are encouraged to upgrade to versions 9.0.81 or 8.5.94 and above to mitigate the risk.
Mitigation & Remediation
Organizations should prioritize upgrading to Apache Tomcat version 9.0.81 or 8.5.94 and above. If an immediate upgrade is not feasible, consider implementing workarounds such as monitoring file uploads to ensure streams are closed properly. Configuration hardening can also help by limiting file upload capabilities to trusted sources.
Monitoring disk usage and implementing alerts for unusual spikes can provide early warning of potential denial of service conditions.
Organizations should consider regular penetration testing to identify similar weaknesses in their applications.
Detection Guidance
Log monitoring should focus on file upload activities, specifically tracking the opening and closing of streams. Behavioral anomalies such as unexpected disk usage spikes should be investigated promptly. Network signatures may also be useful in identifying abnormal file upload patterns.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of thorough testing and validation of file upload functionalities in web applications. As organizations increasingly rely on web applications for critical functions, understanding vulnerabilities like this is essential for maintaining operational integrity. Security teams should remain vigilant and proactive in their approach to vulnerability management.
For further reading on security testing best practices, refer to our resources on penetration testing methodology and consider implementing a comprehensive vulnerability management program to enhance your security posture.
Additionally, reviewing the API penetration testing guide can provide insights into securing your applications further.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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