Executive Summary

This vulnerability exists in aiohttp versions prior to 3.14.1, an asynchronous HTTP client/server framework for Python. During cleanup, the framework could decompress a compressed request body into memory all at once. An attacker could exploit this by sending a specially crafted compressed payload that decompresses into a very large amount of data (a zip bomb edge case), causing excessive memory usage.

The issue arises because certain methods in aiohttp would join all buffered data, including data fed back into the buffer during decompression, leading to unbounded memory allocation. This could crash the server or degrade its performance.

The vulnerability was fixed in version 3.14.1 by changing the logic to limit the amount of data processed during cleanup, preventing unbounded memory consumption.

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Impact Analysis

This vulnerability can lead to a denial-of-service (DoS) condition on servers using vulnerable versions of aiohttp. An attacker can send a malicious compressed payload that decompresses into a very large amount of data, consuming excessive memory.

The excessive memory usage can cause the server to crash or become unresponsive, disrupting service availability.

If the server is critical for your applications or services, this could result in downtime and potential loss of business or user trust.

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Mitigation Strategies

To mitigate this vulnerability, the primary step is to upgrade aiohttp to version 3.14.1 or later, where the issue is fixed.

If upgrading is not immediately possible, a recommended workaround is to disable compression to prevent decompression of malicious payloads that could lead to denial-of-service.

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Compliance Impact

This vulnerability in aiohttp could potentially lead to a denial-of-service (DoS) attack by allowing an attacker to send a compressed payload that decompresses into a large amount of memory, causing excessive resource consumption and server crashes.

While the CVE description and resources do not explicitly mention compliance with standards such as GDPR or HIPAA, denial-of-service vulnerabilities can indirectly impact compliance by affecting the availability and reliability of services that handle sensitive data.

Organizations relying on aiohttp for critical services may need to address this vulnerability promptly to maintain service availability, which is a component of many regulatory requirements.

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Detection Guidance

This vulnerability involves the decompression of compressed HTTP request bodies in aiohttp versions prior to 3.14.1, which can lead to excessive memory usage and potential denial-of-service (DoS). Detection would involve monitoring for unusually large memory consumption or crashes related to handling compressed HTTP requests.

Since the issue is specific to aiohttp server versions up to 3.14.0, the first step is to identify if your system is running a vulnerable aiohttp version.

• Check the aiohttp version installed on your system using the command: `pip show aiohttp` or `python -m pip show aiohttp`.
• If you are running a vulnerable version (<= 3.14.0), monitor your server logs and system metrics for signs of high memory usage or crashes during HTTP request processing.
• To detect potential exploit attempts on the network, you can capture HTTP traffic and look for compressed request bodies (e.g., with Content-Encoding headers like gzip or deflate) that are unusually small but decompress into very large payloads. Tools like Wireshark or tcpdump can be used for this.
• Example command to capture HTTP traffic on port 80: `tcpdump -i any -s 0 -w capture.pcap port 80`
• Analyze captured traffic with Wireshark to filter HTTP requests with compressed bodies and inspect their sizes.

If upgrading aiohttp is not immediately possible, a workaround is to disable compression handling on the server side to mitigate the risk.

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