---
id: "GHSA-5pv8-vvhc-h7jv"
page: "https://infrastack.ai/live/GHSA-5pv8-vvhc-h7jv"
kind: "vulnerability"
aliases: ["GHSA-5pv8-vvhc-h7jv"]
title: "Unbounded cookie storage in client CookieJar"
severity: "low"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "aiohttp", "fixed": ["3.14.4"], "affected": "<= 3.14.3", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["aiohttp", "cwe-1325", "http-client", "package", "python"]
not_affected_if: ["aiohttp-3.14.4-or-later", "server-only-use"]
published_at: "2026-11-08T18:44:21+00:00"
first_seen_at: "2026-11-09T22:53:22+00:00"
updated_at: "2026-11-09T22:58:33+00:00"
sources: [{"source": "ghsa-repo", "url": "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5pv8-vvhc-h7jv", "first_seen_at": "2026-11-09T22:53:22+00:00"}]
exploit_sources: []
---

# Unbounded cookie storage in client CookieJar

Link for people: https://infrastack.ai/live/GHSA-5pv8-vvhc-h7jv (this .md is for agents)

aiohttp's client parsed unrecognised Set-Cookie attributes as extra cookies and its CookieJar had no cap on how many it stored or sent. A malicious server can make the client store huge numbers of cookies and build very large Cookie headers, using excessive memory and CPU.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- pypi:aiohttp affected <= 3.14.3 fixed 3.14.4

## How to check

- Run `pip show aiohttp` and check whether the version is `3.14.3` or older.
- Search the project's requirements or lock files for `aiohttp`.

## Fix

- `aiohttp` `3.14.4`

## Timeline

- 2026-11-09T22:53:22+00:00 ghsa-repo https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5pv8-vvhc-h7jv

## Documents

- [advisory] Maintainer's advisory: github.com https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5pv8-vvhc-h7jv

## From the sources

### Summary

`Set-Cookie` parsing created additional cookies from unrecognised `name=value` attributes, and `CookieJar` had no limit on the number of cookies stored or sent. A server could make the client store a very large number of cookies and generate very large `Cookie` headers.

### Impact

A malicious server could cause excessive memory and CPU use in a client, repeated on every redirect, and cause later requests to the same domain to build an excessively large `Cookie` header.

---

Patch: https://github.com/aio-libs/aiohttp/commit/6963ee0befec1502b6bb7b4db6c72d044c08f4fa

---

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