Executive brief
AIOHTTP is a popular Python library used by developers to build web servers and handle web requests. A flaw in how the library handles compressed data allows an attacker to send a specially crafted "zip bomb" that expands to a massive size in the server's memory during cleanup. This can exhaust the server's resources, causing the application to crash or become unresponsive to legitimate users.
Technical details
AIOHTTP is vulnerable to a Denial of Service (DoS) via a data amplification (zip bomb) attack. The vulnerability exists in the cleanup logic where unread compressed request bodies are decompressed into memory in a single chunk, bypassing 'client_max_size' restrictions. An unauthenticated remote attacker can exploit this by sending a highly compressed payload that expands significantly upon decompression, leading to memory exhaustion. This issue is classified as CWE-409 (Improper Handling of Highly Compressed Data). The vulnerability is fixed in version 3.14.1 by implementing bounded unread compressed drains.
Affected products
- aio-libs aiohttp < 3.14.1
Timeline
- 2026-06-08: advisory: GitHub Security Advisory GHSA-g3cq-j2xw-wf74 published
- 2026-06-22: disclosed: CVE-2026-54278 published to NVD
- 2026-06-22: patched: Fix released in version 3.14.1