CVE-2017-5651 in MySQL Enterprise Monitor
Summary
by MITRE
In Apache Tomcat 9.0.0.M1 to 9.0.0.M18 and 8.5.0 to 8.5.12, the refactoring of the HTTP connectors introduced a regression in the send file processing. If the send file processing completed quickly, it was possible for the Processor to be added to the processor cache twice. This could result in the same Processor being used for multiple requests which in turn could lead to unexpected errors and/or response mix-up.
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Analysis
by VulDB Data Team • 01/04/2021
The vulnerability identified as CVE-2017-5651 represents a critical regression in Apache Tomcat's HTTP connector implementation that emerged during the refactoring process of version 9.0.0.M1 through M18 and 8.5.0 through 8.5.12. This flaw specifically impacts the processor caching mechanism that governs how HTTP requests are handled within the servlet container. The issue stems from improper synchronization during the send file processing operation, creating a scenario where the same processor instance could be inadvertently cached twice. This technical regression fundamentally undermines the request processing integrity that Tomcat relies upon for maintaining separate request contexts and preventing cross-contamination of response data.
The technical execution of this vulnerability occurs when the send file processing completes rapidly, triggering a race condition in the processor management system. During normal operation, each HTTP request should be assigned a unique processor instance from the processor pool to handle the request lifecycle. However, the flawed implementation allows for a processor to be added to the cache twice before the system can properly validate or remove the duplicate entry. This creates a situation where multiple concurrent requests may inadvertently share the same processor instance, leading to severe operational consequences. The vulnerability manifests as a processor cache inconsistency where the same processor object is simultaneously referenced for handling different requests, directly violating fundamental principles of concurrent request processing in web servers.
The operational impact of CVE-2017-5651 extends beyond simple performance degradation to encompass serious security and reliability concerns. When the same processor handles multiple requests simultaneously, there is a high probability of response mix-ups where data intended for one client may be delivered to another, creating potential information disclosure vulnerabilities. The processor's internal state becomes corrupted as it attempts to process multiple request contexts sequentially, leading to unpredictable behavior including malformed responses, data corruption, and potential denial of service conditions. This vulnerability particularly affects applications that rely heavily on file transfer operations or streaming content, as these scenarios are most likely to trigger the rapid send file processing that exposes the race condition. The issue creates a persistent security risk that could be exploited by attackers to gain unauthorized access to sensitive data or disrupt service availability, making it a critical concern for enterprise deployments.
Mitigation strategies for this vulnerability require immediate patching of affected Tomcat versions to the latest stable releases that contain the corrected processor caching implementation. Organizations should prioritize upgrading from the vulnerable versions 9.0.0.M1 through M18 and 8.5.0 through 8.5.12 to versions that have properly addressed the race condition in the send file processing. System administrators should implement monitoring protocols to detect anomalous processor behavior or response mix-ups that may indicate exploitation attempts. The vulnerability aligns with CWE-362, which addresses race conditions in concurrent processing scenarios, and maps to ATT&CK technique T1190 for exploitation of software vulnerabilities. Additional defensive measures include implementing proper request isolation mechanisms, conducting regular security assessments of web application deployments, and maintaining up-to-date security patches across all server components to prevent similar regressions from compromising system integrity.