---
id: CVE-2026-86413
title: Negotiate credentials sent to redirected origin
summary: |-
  When using an *ambient user* in a first transfer doing Negotiate
  authentication and asked to follow redirects, curl could pass on its
  credential details to an unrelated second origin when asked to redirect there.
severity: none
cwe:
  - CWE-201
vendor: curl
product: curl
affected:
  - curl >= 8.22.0 <= 8.22.0
  - curl >= 8.21.0 <= 8.21.0
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T20:06:11.699Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-86413'
references:
  - url: 'https://curl.se/docs/CVE-2026-86413.json'
    label: json
  - url: 'https://curl.se/docs/CVE-2026-86413.html'
    label: www
  - url: 'https://hackerone.com/reports/3993549'
    label: issue
tags:
  - cve.org
ingestedAt: '2026-10-20T20:18:14.525Z'
---

## Overview

When using an *ambient user* in a first transfer doing Negotiate
authentication and asked to follow redirects, curl could pass on its
credential details to an unrelated second origin when asked to redirect there.

## Affected

- `curl >= 8.22.0 <= 8.22.0`
- `curl >= 8.21.0 <= 8.21.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.