AIOHTTP: Cookie from Subdomain Can Remove Host-Only Scope from Existing Cookies
Summary
In aiohttp, a subdomain can remove the Host-Only flag from an existing cookie associated with a parent domain.
Impact
A user accessing untrusted subdomains could see their Host-Only protections stripped from cookies. Given that most use cases will not reflect these cookies to a browser, the impact is limited.
What to do
Upgrade aiohttp to version 3.14.4 or later.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | aiohttp | < 3.14.4 | 3.14.4 |
References
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-gx76-c99x-2c96
- https://nvd.nist.gov/vuln/detail/CVE-2026-111749
- https://github.com/aio-libs/aiohttp/commit/6a07c171ef9f3be583e2907dcd1931372efca8d6
- https://github.com/aio-libs/aiohttp
- https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-565- Platform
- Python (PyPI)
- Package
aiohttp- Disclosed
- 20.10.2026
- Updated
- 20.10.2026 23:23
Sources and licenses · Edited or translated by DockRay; source rights and applicable licenses are retained.
OSV / GitHub Advisory Database - GHSA-gx76-c99x-2c96 - CC BY 4.0
Vulnerability history: aiohttp
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 55
- First → latest
- 02.2021 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 7
- Medium 29
- Low 19
Disclosures per year
- 2021: 1
- 2022: 0
- 2023: 6
- 2024: 7
- 2025: 1
- 2026: 40
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