CVE-2024-52303 in aiohttp
Summary
by MITRE • 11/18/2024
aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. In versions starting with 3.10.6 and prior to 3.10.11, a memory leak can occur when a request produces a MatchInfoError. This was caused by adding an entry to a cache on each request, due to the building of each MatchInfoError producing a unique cache entry. An attacker may be able to exhaust the memory resources of a server by sending a substantial number (100,000s to millions) of such requests. Those who use any middlewares with aiohttp.web should upgrade to version 3.10.11 to receive a patch.
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Analysis
by VulDB Data Team • 08/15/2025
The aiohttp framework represents a critical vulnerability in its asynchronous http client/server implementation that manifests through memory exhaustion attacks targeting version 3.10.6 through 3.10.10. This vulnerability stems from improper cache management during error handling processes, specifically when MatchInfoError exceptions are generated. The flaw occurs because each MatchInfoError instance creates a unique cache entry, leading to unbounded memory consumption as requests are processed. The security implications extend beyond simple resource exhaustion since this vulnerability can be exploited by attackers to perform denial of service attacks against applications relying on aiohttp's web server capabilities. The vulnerability affects systems where middlewares are utilized, making it particularly dangerous in production environments where aiohttp serves as a core component of web application infrastructure.
The technical root cause of CVE-2024-52303 lies in the improper handling of cache entries during exception processing within the routing mechanism of aiohttp. When a request triggers a MatchInfoError, the framework's internal cache management system creates a new entry without proper deduplication or cleanup mechanisms. This results in a memory leak where each erroneous request contributes to growing cache size, with each unique MatchInfoError producing a separate cache entry. The vulnerability aligns with CWE-400, which addresses improper resource management in software systems, specifically focusing on memory leaks that occur due to inadequate resource cleanup. The implementation flaw demonstrates poor memory management practices where the framework fails to recognize that multiple requests can generate identical MatchInfoError instances, yet still creates separate cache entries for each occurrence.
The operational impact of this vulnerability extends beyond simple memory exhaustion, creating potential cascading failures in web applications that rely on aiohttp for handling concurrent requests. Attackers can exploit this weakness by sending massive volumes of malformed requests, potentially reaching into the hundreds of thousands or millions of requests, to systematically consume available memory resources. This attack vector represents a classic denial of service scenario where legitimate system resources are consumed by malicious actors, preventing the application from serving legitimate requests. The vulnerability's severity is amplified when considering that many modern web applications rely on middleware components, which increases the attack surface and makes systems more susceptible to exploitation. The memory leak can cause applications to crash, become unresponsive, or experience significant performance degradation, effectively rendering the service unavailable to legitimate users.
Mitigation of CVE-2024-52303 requires immediate upgrading to aiohttp version 3.10.11 or later, which contains the necessary patch to address the cache management issue. Organizations should implement monitoring systems to detect unusual memory consumption patterns that may indicate exploitation attempts, particularly in environments where aiohttp is used with middleware components. The patch addresses the root cause by implementing proper cache deduplication mechanisms and ensuring that identical MatchInfoError instances do not generate multiple cache entries. Security teams should also consider implementing rate limiting and request validation mechanisms as additional defensive measures. The vulnerability highlights the importance of proper resource management in asynchronous frameworks and underscores the need for comprehensive testing of error handling paths in high-concurrency environments. System administrators should conduct thorough testing of the patched version in staging environments before deploying to production systems to ensure compatibility with existing middleware configurations and application logic.