# AIOHTTP is vulnerable to cross-origin redirect with per-request cookies

Advisory record · `GHSA-hg6j-4rv6-33pg`

- **Identifiers:** `GHSA-hg6j-4rv6-33pg` · `CVE-2026-47265` · `PYSEC-2026-2105`
- **State:** Confirmed
- **Severity:** CVSS 6.6 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-346](https://cwe.mitre.org/data/definitions/346.html)
- **Tags:** [CWE-346](https://agentprime.io/advisories/tag/cwe-346.md)
- **Published:** 3 Jun 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 3 Jun 2026, 21:34 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `aiohttp` (PyPI): affected `<3.14.0`; fixed in `3.14.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> AIOHTTP versions before 3.14.0 are vulnerable: cookies passed with the per-request cookies parameter are sent after following a cross-origin redirect. An attacker who can control a redirect could receive those cookies and leak sensitive data. Upgrade to aiohttp 3.14.0 or later; if upgrading is not possible, pass cookies through a Cookie header in the headers parameter instead.

Written 4 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.6 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0015, the 4th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 2 Jun 2026, 12:26 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/aio-libs/aiohttp/security/advisories/GHSA-hg6j-4rv6-33pg)
- 31 Oct 2026, 14:29 UTC: First seen by agentprime
- 31 Oct 2026, 14:29 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-hg6j-4rv6-33pg)

## Sources

- [GitHub Advisory Database: GHSA-hg6j-4rv6-33pg](https://github.com/advisories/GHSA-hg6j-4rv6-33pg)
- [OSV: GHSA-hg6j-4rv6-33pg](https://osv.dev/vulnerability/GHSA-hg6j-4rv6-33pg)
- <https://github.com/aio-libs/aiohttp/security/advisories/GHSA-hg6j-4rv6-33pg>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-47265>
- <https://github.com/aio-libs/aiohttp/commit/f54c40851b0d6c4bbdab97ba518a223adda32478>
- <https://github.com/aio-libs/aiohttp>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-hg6j-4rv6-33pg>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-hg6j-4rv6-33pg/>. Everything for agents: <https://agentprime.io/llms.txt>.