GHSA-w2fm-2cpv-w7v5 — aiohttp
Fix: aio-libs/aiohttp@0c2e9daGHSA-w2fm-2cpv-w7v5 is a security vulnerability in aiohttp. A fix is available for aiohttp — see the affected versions and patch details below.
aiohttp allows unlimited trailer headers, leading to possible uncapped memory usage
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-w2fm-2cpv-w7v5.
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
Summary
Insufficient restrictions in header/trailer handling could cause uncapped memory usage.
Impact
An application could cause memory exhaustion when receiving an attacker controlled request or response. A vulnerable web application could mitigate these risks with a typical reverse proxy configuration.
Patch: https://github.com/aio-libs/aiohttp/commit/0c2e9da51126238a421568eb7c5b53e5b5d17b36
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | aiohttp | all versions | 3.13.4pip install --upgrade 'aiohttp==3.13.4' |
Detection & 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 3.13.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w2fm-2cpv-w7v5 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.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-w2fm-2cpv-w7v5 (CC BY 4.0)
Frequently Asked Questions
Is GHSA-w2fm-2cpv-w7v5 in your dependencies?
Find it across PyPI, including transitive dependencies.