CVE-2024-52303: aiohttp memory leak when middleware is enabled when requesting a resource with a non-allowed method

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-11-18 · updated 2026-06-17
Weakness: CWE-772

Description

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.

Affected products

aio-libs aiohttp: from 3.10.6 before 3.10.11 — fixed in 3.10.11

How to fix

Upgrade to a fixed version: aio-libs aiohttp 3.10.11. Check the vendor advisory for mitigations.

References

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