---
id: CVE-2023-27537
title: >-
  A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data
  between separate "handles"
summary: >-
  A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data
  between separate "handles". This sharing was introduced without considerations
  for do this sharing across separate threads but there was no indication of
  this fa…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-415
vendor: haxx
product: libcurl
affected:
  - libcurl = 7.88.0
  - libcurl = 7.88.1
  - active_iq_unified_manager
  - clustered_data_ontap = 9.0
  - brocade_fabric_operating_system_firmware
  - h300s_firmware
  - h500s_firmware
  - h700s_firmware
  - h410s_firmware
  - '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: '2026-10-14T23:17:16.843'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-27537'
references:
  - url: 'https://hackerone.com/reports/1897203'
    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/1897203'
    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-943925.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.01856
epssPercentile: 0.78769
ingestedAt: '2026-10-15T00:02:07.131Z'
---

## Overview

A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free.

## Affected

- `libcurl = 7.88.0`
- `libcurl = 7.88.1`
- `active_iq_unified_manager`
- `clustered_data_ontap = 9.0`
- `brocade_fabric_operating_system_firmware`
- `h300s_firmware`
- `h500s_firmware`
- `h700s_firmware`
- `h410s_firmware`
- `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`