---
id: CVE-2026-5773
title: |-
  libcurl might in some circumstances reuse the wrong connection for SMB(S)
  transfers.

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

  When reusing a connectio…
summary: |-
  libcurl might in some circumstances reuse the wrong connection for SMB(S)
  transfers.

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

  When reusing a connectio…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-488
  - CWE-918
vendor: haxx
product: curl
affected:
  - 'curl >= 7.40.0, < 8.20.0'
patched:
  - curl 8.20.0
published: '2026-05-13'
updated: '2026-09-15'
sourceUpdated: '2026-09-15T07:16:28.820'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-5773'
references:
  - url: 'https://curl.se/docs/CVE-2026-5773.html'
    label: 2499f714-1537-4658-8207-48ae4bb9eae9
  - url: 'https://curl.se/docs/CVE-2026-5773.json'
    label: 2499f714-1537-4658-8207-48ae4bb9eae9
  - url: 'https://hackerone.com/reports/3650689'
    label: 2499f714-1537-4658-8207-48ae4bb9eae9
  - url: 'http://www.openwall.com/lists/oss-security/2026/04/29/9'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://hackerone.com/reports/3650689'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-05-13T17:45:00.901945Z'
epss: 0.00618
epssPercentile: 0.47948
ingestedAt: '2026-09-15T07:33:29.265Z'
---

## Overview

libcurl might in some circumstances reuse the wrong connection for SMB(S)
transfers.

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 network transfer operation that was requested by an
application could wrongfully reuse an existing SMB connection to the same
server that was using a different "share" than the new subsequent transfer
should.

This could in unlucky situations lead to the download of the wrong file or the
upload of a file to the wrong place. When this happens, the same credentials
are used and the server name is the same.

## Affected

- `curl >= 7.40.0, < 8.20.0`

## Remediation

Upgrade past the affected range:

- `curl 8.20.0`