AIOHTTP Vulnerable to Cookie Parser Warning StormGHSA-fh55-r93g-j68g
Fix: aio-libs/aiohttp@64629a0GHSA-fh55-r93g-j68g is a CWE-779 vulnerability in aiohttp. A fix is available for aiohttp — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-fh55-r93g-j68g.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
aiohttpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. In versions 3.13.2 and below, reading multiple invalid cookies can lead to a logging storm. If the cookies attribute is accessed in an application, then an attacker may be able to trigger a storm of warning-level logs using a specially crafted Cookie header. This issue is fixed in 3.13.3.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | aiohttp | all versions | 3.13.3pip install --upgrade 'aiohttp==3.13.3' |
Affected Products
aiohttpaiohttpDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for aiohttp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update aiohttp to 3.13.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fh55-r93g-j68g is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated Low for Red Hat products. A flaw in aiohttp allows a remote attacker to trigger a logging storm by sending specially crafted invalid cookies, leading to resource exhaustion and a Denial of Service condition. This impact occurs if the application accesses the cookies attribute.
No mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.Source: Red Hat security advisory for GHSA-fh55-r93g-j68g (CC BY 4.0)
Frequently Asked Questions
Is GHSA-fh55-r93g-j68g in your dependencies?
Find it across PyPI, including transitive dependencies.