---
id: CVE-2026-86415
title: auto client cert connection reuse mixup
summary: |-
  libcurl's connection cache match function never considers the automatic client
  certificate option, so a cached, already authenticated Schannel connection can
  be handed to a transfer that got redirected to a different origin, even though
  …
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: '2026-10-20T20:08:29.941Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-86415'
references:
  - url: 'https://curl.se/docs/CVE-2026-86415.json'
    label: json
  - url: 'https://curl.se/docs/CVE-2026-86415.html'
    label: www
  - url: 'https://hackerone.com/reports/3993870'
    label: issue
tags:
  - cve.org
ingestedAt: '2026-10-20T21:19:21.287Z'
---

## Overview

libcurl's connection cache match function never considers the automatic client
certificate option, so a cached, already authenticated Schannel connection can
be handed to a transfer that got redirected to a different origin, even though
the code explicitly switched off the auto client cert option for that transfer
to prevent exactly this.

## 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.