Vulnerability · Published Oct 19, 2026 · Assigned by GitHub_M

CVE-2026-111749AIOHTTP: Cookie from subdomain can remove Host-Only Scope from existing cookies

Low 2.3

In plain English

A low-severity security flaw in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)2.3Low

Exploit odds (30 days)0.4%top 67.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	python-aiohttp	no fix listed	DEBIAN-CVE-2026-111749
Debian:13	python-aiohttp	no fix listed	DEBIAN-CVE-2026-111749
Debian:14	python-aiohttp	no fix listed	DEBIAN-CVE-2026-111749
PyPI	aiohttp	3.14.4	GHSA-gx76-c99x-2c96
Ubuntu:26.10	python-aiohttp	no fix listed	UBUNTU-CVE-2026-111749

Affected products (as reported)

Vendor	Product	Versions
aio-libs	aiohttp	< 3.14.4

Weakness: CWE-565 · 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

References

https://github.com/aio-libs/aiohttp/security/advisories/GHSA-gx76-c99x-2c96 x_refsource_CONFIRM
https://github.com/aio-libs/aiohttp/commit/6a07c171ef9f3be583e2907dcd1931372efca8d6 x_refsource_MISC
https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4 x_refsource_MISC