---
id: CVE-2023-27536
title: >-
  An authentication bypass vulnerability exists libcurl <8.0.0 in the connection
  reuse feature which can reuse previously established connections with
  incorrect user permissions due to a failure to check for changes in the
  CURLOPT_GSSAPI_D…
summary: >-
  An authentication bypass vulnerability exists libcurl <8.0.0 in the connection
  reuse feature which can reuse previously established connections with
  incorrect user permissions due to a failure to check for changes in the
  CURLOPT_GSSAPI_D…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-305
  - CWE-287
vendor: haxx
product: libcurl
affected:
  - 'libcurl >= 7.22.0, <= 7.88.1'
  - fedora = 36
  - debian_linux = 10.0
  - active_iq_unified_manager
  - h300s_firmware
  - h500s_firmware
  - h700s_firmware
  - h410s_firmware
  - ontap = 9
  - 'universal_forwarder >= 8.2.0, < 8.2.12'
  - 'universal_forwarder >= 9.0.0, < 9.0.6'
  - universal_forwarder = 9.1.0
patched:
  - universal_forwarder 9.0.6
published: '2023-03-30'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T23:17:16.650'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-27536'
references:
  - url: 'https://hackerone.com/reports/1895135'
    label: support@hackerone.com
  - url: 'https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html'
    label: support@hackerone.com
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERWRYJQ6LAQW/
    label: support@hackerone.com
  - url: 'https://security.gentoo.org/glsa/202310-12'
    label: support@hackerone.com
  - url: 'https://security.netapp.com/advisory/ntap-20230420-0010/'
    label: support@hackerone.com
  - url: 'https://hackerone.com/reports/1895135'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERWRYJQ6LAQW/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202310-12'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20230420-0010/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-806742.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-943925.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.01566
epssPercentile: 0.74819
ingestedAt: '2026-10-15T00:02:07.130Z'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2025-02-14T15:39:19.648695Z'
---

## Overview

An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPT_GSSAPI_DELEGATION option. This vulnerability affects krb5/kerberos/negotiate/GSSAPI transfers and could potentially result in unauthorized access to sensitive information. The safest option is to not reuse connections if the CURLOPT_GSSAPI_DELEGATION option has been changed.

## Affected

- `libcurl >= 7.22.0, <= 7.88.1`
- `fedora = 36`
- `debian_linux = 10.0`
- `active_iq_unified_manager`
- `h300s_firmware`
- `h500s_firmware`
- `h700s_firmware`
- `h410s_firmware`
- `ontap = 9`
- `universal_forwarder >= 8.2.0, < 8.2.12`
- `universal_forwarder >= 9.0.0, < 9.0.6`
- `universal_forwarder = 9.1.0`

## Remediation

Upgrade past the affected range:

- `universal_forwarder 9.0.6`