---
id: "CVE-2026-54279"
kind: "vulnerability"
aliases: ["CVE-2026-54279", "GHSA-2fqr-mr3j-6wp8"]
title: "aiohttp: Host-Only Cookies Become Domain Cookies After CookieJar Persistence"
severity: "high"
cvss: 7.5
epss: 0.00493
exploited: false
status: "open"
category: "package"
products: [{"name": "aiohttp", "fixed": ["3.14.1"], "affected": "<= 3.14.0", "ecosystem": "pypi"}, {"name": "aiohttp", "fixed": ["3.14.1"], "affected": "< 3.14.1", "ecosystem": "vendor"}]
ecosystems: ["pypi", "vendor"]
tags: ["aiohttp", "cwe-665", "http-clients", "package", "python"]
not_affected_if: ["fixed-version", "no-cookie-persistence"]
published_at: "2026-06-15T20:08:51+00:00"
first_seen_at: "2026-11-03T16:30:30+00:00"
updated_at: "2026-11-03T16:51:48+00:00"
sources: [{"source": "ghsa", "url": "https://github.com/advisories/GHSA-2fqr-mr3j-6wp8", "first_seen_at": "2026-11-03T16:30:30+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54279", "first_seen_at": "2026-11-03T16:51:48+00:00"}]
---

# aiohttp: Host-Only Cookies Become Domain Cookies After CookieJar Persistence

aiohttp's CookieJar loses the host-only flag on cookies it restores from disk via load(). Those cookies can then be sent to subdomains that should not receive them.

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

## Affected

- pypi:aiohttp affected <= 3.14.0 fixed 3.14.1
- vendor:aiohttp affected < 3.14.1 fixed 3.14.1

## How to check

- Run `pip show aiohttp` and compare the version to `3.14.0`
- Search your code for `CookieJar` together with `.load(` or `.save(`

## Fix

- `aiohttp` `3.14.1`

## Timeline

- 2026-11-03T16:30:30+00:00 ghsa https://github.com/advisories/GHSA-2fqr-mr3j-6wp8
- 2026-11-03T16:51:48+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-54279

## Documents

- [advisory] Maintainer's advisory: api.github.com https://api.github.com/repos/aio-libs/aiohttp/security-advisories/GHSA-2fqr-mr3j-6wp8
- [advisory] Maintainer's advisory: github.com https://github.com/aio-libs/aiohttp/security/advisories/GHSA-2fqr-mr3j-6wp8
- [fix] Patch: github.com https://github.com/aio-libs/aiohttp/commit/a329a7aacad5284f087af36103aff778746da0f2

## From the sources

### Summary

Host-only cookies that are saved with ``CookieJar.save()`` and then restored later with ``CookieJar.load()`` lose their host-only status.

### Impact

Host-only cookies that have been loaded from disk may get sent to subdomains that previously should have been disallowed.

-----

Patch: https://github.com/aio-libs/aiohttp/commit/a329a7aacad5284f087af36103aff778746da0f2

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_