In short
- CVE-2026-111749 is a LOW (CVSS 2.3) vulnerability affecting aiohttp.
- Chance of exploitation in the next 30 days (EPSS): 0.38%, higher than 32.5% of all vulnerabilities.
- Fix: update to 3.14.4 or later.
| Package | Affected versions | Patched versions |
|---|
| aiohttp PyPI | < 3.14.4
| 3.14.4
|
Description
Summary
A subdomain can remove the Host-Only flag from an existing cookie to a parent domain.
Impact
A user accessing untrusted subdomains could see their Host-Only protections stripped from cookies. Given most usecases won't reflect these cookies to a browser, the impact is limited.
NVD description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, Host-Only scope on an existing parent-domain cookie can be removed by a subdomain. A user who accesses an untrusted subdomain can consequently have host-only protections stripped from cookies, although impact is limited when applications do not reflect those cookies to a browser. This issue is fixed in version 3.14.4.
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