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Findings

CVE-2023-27537

A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles".

Published Mar 30, 2023 · corrected/updated Oct 14, 2026 · haxx libcurl · evidence confidence high

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.

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2023-27537 is a medium public vulnerability record for haxx libcurl. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether haxx libcurl is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: broadcom/brocade fabric operating system firmware; haxx/libcurl (7.88.0); haxx/libcurl (7.88.1); netapp/active iq unified manager. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: CVSS 5.9, EPSS 1.9%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-415. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in the CISA KEV catalog.

  • Patch and remediation

    No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 30, 2023 · NIST NVD

    Detected

    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.

  2. Oct 14, 2026 · NIST NVD

    Updated

    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

  • cpe broadcom/brocade fabric operating system firmwareversion unspecified
  • cpe haxx/libcurl7.88.0
  • cpe haxx/libcurl7.88.1
  • cpe netapp/active iq unified managerversion unspecified
  • cpe netapp/clustered data ontap9.0
  • cpe netapp/h300s firmwareversion unspecified
  • cpe netapp/h410s firmwareversion unspecified
  • cpe netapp/h500s firmwareversion unspecified
  • cpe netapp/h700s firmwareversion unspecified
  • cpe splunk/universal forwarderversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2023-27537

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-27537

    30-day exploitation probability 1.9%

    first.org
  • NIST NVDVulnerability recordCVE-2023-27537

    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 mut

    nvd.nist.gov

References