What is CVE-2026-47265?

CVE-2026-47265 is a high-severity vulnerability in Aiohttp, classified under Origin Validation Error. CVSS score: 7.5/10. Published 2026-06-02.

How severe is CVE-2026-47265?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Aiohttp

CVE-2026-47265

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.14.0, cookies set with the `cookies` parameter on requests are sent after following a cross-origin redirect. If a developer uses the `cookies` parameter on a per-request basis then sensitive data might be leaked to an attacker if they manage to control a redirect. Version 3.14.0 patches the issue. If unable to upgrade, using a `Cookie` header in the `headers` parameter is not vulnerable.

Published 2026-06-02 · last modified 2026-07-21.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.002 (10.9th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 10.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.001

Affected products

Aiohttp
Aio-Libs Aiohttp — versions < 3.14.0

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

github.com/aio-libs/aiohttp/security/advisories/GHSA-hg6j-4rv6-33pg (Patch, Mitigation, Vendor Advisory)
github.com/aio-libs/aiohttp/commit/f54c40851b0d6c4bbdab97ba518a223adda32478 (Patch)

Frequently asked questions

What is CVE-2026-47265?: CVE-2026-47265 is a high-severity vulnerability in Aiohttp, classified under Origin Validation Error. CVSS score: 7.5/10. Published 2026-06-02.
How severe is CVE-2026-47265?: High severity. CVSS v3 base score is 7.5 out of 10.