ZeroDay Findings
Sign inSign up

Findings

CVE-2023-27538

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option wa…

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

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

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-2023-27538 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; debian/debian linux (10.0); fedoraproject/fedora (36); haxx/libcurl. 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 5.5, EPSS 1.5%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-287, CWE-305. 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

    An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration

  2. Oct 14, 2026 · NIST NVD

    Updated

    An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration

Affected

  • cpe broadcom/brocade fabric operating system firmwareversion unspecified
  • cpe debian/debian linux10.0
  • cpe fedoraproject/fedora36
  • cpe haxx/libcurlversion unspecified
  • 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-2023-27538

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-27538

    30-day exploitation probability 1.5%

    first.org
  • NIST NVDVulnerability recordCVE-2023-27538

    An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse t

    nvd.nist.gov

References