CVE-2026-54278: AIOHTTP: Unread Compressed Request Bodies Bypass client_max_size During Cleanup

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-22 · updated 2026-10-25
Weakness: CWE-409

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, during cleanup it is possible for a compressed request body to be decompressed into memory in one chunk. An attacker may be able to send a compressed payload in specific situations that could be decompressed into memory, potentially leading to DoS (a zip bomb edge case). This vulnerability is fixed in 3.14.1.

Affected products

aio-libs aiohttp: before 3.14.1 — fixed in 3.14.1
Pypi Aiohttp: before 3.14.1; 0.1, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 0.12.0 (+301) — fixed in 3.14.1

How to fix

Upgrade to a fixed version: aio-libs aiohttp 3.14.1; Pypi Aiohttp 3.14.1. Check the vendor advisory for mitigations.

References

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