---
schema_version: '1.0'
id: security-20260705-4d15b8
url: https://osv.dev/vulnerability/CURL-CVE-2026-5545
url_hash: 4d15b8e85e16a7bf3ec87a2037005b106cd70ccca0e8bc0b5e297bfc43c8dcbe
canonical_url: https://osv.dev/vulnerability/CURL-CVE-2026-5545
source: osv:osv
category: security/library
category_raw: cve/library
region: null
tags:
- cve
- CVE-2026-5545
- CURL-CVE-2026-5545
- severity:Medium
- https://github.com/curl/curl
- GIT
lang: en
published_at: '2026-04-29T08:00:00Z'
fetched_at: '2026-07-05T15:34:34Z'
updated_at: '2026-07-05T15:37:46Z'
status: published
content_hash: 1985993c77ca3aab748dcd72b6b8fc03a5e675b30828ca90637e319e789ca680
license_note: full
summary: wrong reuse of HTTP Negotiate connection
summary_source: rss
summary_en: wrong reuse of HTTP Negotiate connection
entities:
- name: GitHub
  type: organization
- name: HTTP Request-Response Structure
  type: concept
key_facts: []
related: []
related_auto:
- name: Intent-centric Protocol
  type: UNKNOWN
  weight: 2.0
- name: Anonymous
  type: organization
  weight: 1.0
- name: AirPods
  type: artifact
  weight: 1.0
- name: Claude Code
  type: artifact
  weight: 1.0
- name: セッション漏洩
  type: event
  weight: 1.0
title: 'CVE-2026-5545: wrong reuse of HTTP Negotiate connection'
---

# CVE-2026-5545: wrong reuse of HTTP Negotiate connection

## TL;DR
wrong reuse of HTTP Negotiate connection

## Key Points
- cve / CVE-2026-5545 / CURL-CVE-2026-5545 / severity:Medium / https://github.com/curl/curl / GIT

## Details
**Severity:** Medium
**Advisory:** CURL-CVE-2026-5545 (CVE-2026-5545)

**Affected (your watchlist):**
- `GIT:https://github.com/curl/curl` curl-8_9_1 → no fixed version listed [mac]

**Details:**
libcurl might in some circumstances reuse the wrong connection when asked to
do an authenticated HTTP(S) request after a Negotiate-authenticated one, when
both use the same host.

libcurl features a pool of recent connections so that subsequent requests can
reuse an existing connection to avoid overhead.

When reusing a connection a range of criteria must be met. Due to a logical
error in the code, a request that was issued by an application could
wrongfully reuse an existing connection to the same server that was
authenticated using different credentials.

An application that first uses Negotiate authentication to a server with
`user1:password1` and then does another operation to the same server asking
for any authentication method but for `user2:password2` (while the previous
connection is still alive) - the second request gets confused and wrongly
reuses the same connection and sends the new request over that connection
thinking it uses a mix of user1's and user2's credentials when it is in fact
still using the connection authenticated for user1...

_Data: OSV.dev (upstream: osv) — https://osv.dev/vulnerability/CURL-CVE-2026-5545_

## Source
元記事: [CVE-2026-5545: wrong reuse of HTTP Negotiate connection](https://osv.dev/vulnerability/CURL-CVE-2026-5545) — published 2026-04-29T08:00:00Z