CVE-2025-69227: AIOHTTP vulnerable to DoS when bypassing asserts
Summary When assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body.
Impact If optimisations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message.
------
Patch: https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259
Other sources
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below allow for an infinite loop to occur when assert statements are bypassed, resulting in a DoS attack when processing a POST body. If optimizations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message. This issue is fixed in version 3.13.3.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/aiohttpto a version that resolves this vulnerability.Fixed in 3.13.3 - Upgrade
Upgrade
aiohttpto a version that resolves this vulnerability.Fixed in 3.13.3 - Compensating control
If you cannot immediately upgrade, disable Python optimizations (do not use -O or set PYTHONOPTIMIZE=1) to prevent assert statements from being bypassed in aiohttp Request.post() handling.
Event History
Frequently Asked Questions
What is the severity of CVE-2025-69227?
CVE-2025-69227 is classified as a denial of service (DoS) vulnerability due to an infinite loop that can be triggered.
How do I fix CVE-2025-69227?
To address CVE-2025-69227, you should upgrade the aiohttp package to version 3.13.3 or later.
Which versions of aiohttp are affected by CVE-2025-69227?
CVE-2025-69227 affects aiohttp versions up to and including 3.13.2.
What conditions must be met for CVE-2025-69227 to be exploited?
CVE-2025-69227 can be exploited when optimizations are enabled and the application calls the Request.post() method.
What impact does CVE-2025-69227 have on applications?
The impact of CVE-2025-69227 is that it can lead to denial of service due to an infinite loop during POST body processing.