# async-http-client: Cookie header not stripped on cross-origin redirect

Advisory record · `GHSA-fmxf-pm6p-7xgm`

- **Identifiers:** `GHSA-fmxf-pm6p-7xgm` · `CVE-2026-45300`
- **State:** Confirmed
- **Severity:** CVSS 7.4 High
- **Critical:** No
- **Weakness (CWE):** [CWE-200](https://cwe.mitre.org/data/definitions/200.html)
- **Tags:** [Information disclosure](https://agentprime.io/advisories/tag/info-disclosure.md)
- **Published:** 18 May 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 18 May 2026, 16:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `org.asynchttpclient:async-http-client` (Maven): affected `>=3.0.0.Beta1, <3.0.10 || >=2.0.0, <2.15.0`; fixed in `3.0.10`, `2.15.0`

## Machine-written summary

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

> Versions of org.asynchttpclient:async-http-client from 3.0.0.Beta1 before 3.0.10, and from 2.0.0 before 2.15.0, do not remove the Cookie header when following a redirect to a different origin or when the redirect downgrades from HTTPS to HTTP. An attacker who can supply a redirect target, such as through an open redirect, a compromised gateway, or a man-in-the-middle position on a plaintext hop, can receive session cookies and other cookie values. Upgrade to 3.0.10 or 2.15.0, which are the fixed versions.

Written 2 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

- 7.4 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0040, the 34th percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:17 UTC: First seen by agentprime
- 31 Oct 2026, 14:17 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-fmxf-pm6p-7xgm)

## Sources

- [GitHub Advisory Database: GHSA-fmxf-pm6p-7xgm](https://github.com/advisories/GHSA-fmxf-pm6p-7xgm)
- [OSV: GHSA-fmxf-pm6p-7xgm](https://osv.dev/vulnerability/GHSA-fmxf-pm6p-7xgm)
- <https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-fmxf-pm6p-7xgm>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-45300>
- <https://github.com/AsyncHttpClient/async-http-client/commit/3b0e3e9e>
- <https://github.com/AsyncHttpClient/async-http-client>
- <https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-3.0.10>

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-fmxf-pm6p-7xgm>, 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-fmxf-pm6p-7xgm/>. Everything for agents: <https://agentprime.io/llms.txt>.