CVE-2025-69223 is a vulnerability identified in aiohttp, a popular asynchronous HTTP client/server framework used in Python applications. Versions prior to 3.13.3 are susceptible to a denial-of-service (DoS) attack via a zip bomb, a form of data amplification attack. The vulnerability arises from improper handling of highly compressed data (CWE-409) and inadequate restriction on resource consumption during decompression (CWE-770). An attacker can send a maliciously crafted compressed HTTP request that, when decompressed by the aiohttp server, consumes excessive memory resources, potentially exhausting the host's available memory and causing the server to crash or become unresponsive. This attack vector requires no authentication or user interaction and can be executed remotely over the network. The CVSS v3.1 score of 7.5 reflects the high impact on availability with low attack complexity and no privileges required. Although no known exploits are currently in the wild, the vulnerability poses a significant risk to any aiohttp-based services that accept compressed HTTP requests. The issue was addressed in aiohttp version 3.13.3 by implementing safeguards against excessive resource consumption during decompression.

For European organizations, this vulnerability can lead to significant service disruptions, especially for those relying on aiohttp for web servers, APIs, or microservices. The DoS attack can cause outages, impacting business continuity, customer trust, and potentially leading to financial losses. Critical sectors such as finance, healthcare, government, and telecommunications that deploy aiohttp-based services are particularly vulnerable to operational interruptions. Additionally, organizations hosting public-facing services may face increased risk from automated or targeted attacks exploiting this flaw. The lack of confidentiality or integrity impact limits data breach concerns, but the availability impact alone can be severe, especially in environments with high availability requirements or strict service-level agreements (SLAs).

The primary mitigation is to upgrade all aiohttp deployments to version 3.13.3 or later, where the vulnerability is fixed. Organizations should audit their Python environments to identify and remediate vulnerable aiohttp versions promptly. Additionally, implementing strict limits on decompression resource usage—such as maximum decompressed size, memory usage caps, and request size limits—can reduce the risk of exploitation. Network-level protections like rate limiting, web application firewalls (WAFs) configured to detect anomalous compressed payloads, and anomaly detection systems can provide additional defense layers. Monitoring server memory usage and setting up alerts for unusual spikes can help detect ongoing attacks early. Finally, developers should avoid accepting compressed requests from untrusted sources or implement validation to reject suspicious payloads.