# CVE-2023-27537: CVE-2023-27537

Status: published. Published: 2023-03-30. Updated: 2026-11-02.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- n/a / https://github.com/curl/curl: Fixed in 8.0.0 (affected). Source: CNA: hackerone
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:haxx:libcurl:7.88.0:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:haxx:libcurl:7.88.1:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  },
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:netapp:clustered_data_ontap:9.0:-:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:broadcom:brocade_fabric_operating_system_firmware:-:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  },
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      },
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:*",
            "vulnerable": false
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "AND"
  },
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      },
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:*",
            "vulnerable": false
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "AND"
  },
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      },
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:*",
            "vulnerable": false
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "AND"
  },
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      },
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:*",
            "vulnerable": false
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "AND"
  },
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "8.2.12",
            "versionStartIncluding": "8.2.0",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "9.0.6",
            "versionStartIncluding": "9.0.0",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:splunk:universal_forwarder:9.1.0:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]
```

## Severity and prioritization

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: nvd@nist.gov

- CISA KEV: No listing in collected sources

- EPSS: 1.90% as of 2026-11-02; percentile 79.65%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-415

## Exploit evidence

- exploit: https://hackerone.com/reports/1897203 (support@hackerone.com)
- exploit: https://hackerone.com/reports/1897203 (af854a3a-2127-422b-91ae-364da2661108)

## References

- https://hackerone.com/reports/1897203 (CNA: hackerone)

- https://security.netapp.com/advisory/ntap-20230420-0010/ (CNA: hackerone)

- https://security.gentoo.org/glsa/202310-12 (CNA: hackerone; vendor-advisory)

- https://hackerone.com/reports/1897203 (ADP: CVE; x_transferred)

- https://security.netapp.com/advisory/ntap-20230420-0010/ (ADP: CVE; x_transferred)

- https://security.gentoo.org/glsa/202310-12 (ADP: CVE; vendor-advisory, x_transferred)

- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-943925.html (ADP: siemens-SADP)

- https://hackerone.com/reports/1897203 (support@hackerone.com; Exploit, Third Party Advisory)

- https://security.gentoo.org/glsa/202310-12 (support@hackerone.com; Third Party Advisory)

- https://security.netapp.com/advisory/ntap-20230420-0010/ (support@hackerone.com; Third Party Advisory)

- https://hackerone.com/reports/1897203 (af854a3a-2127-422b-91ae-364da2661108; Exploit, Third Party Advisory)

- https://security.gentoo.org/glsa/202310-12 (af854a3a-2127-422b-91ae-364da2661108; Third Party Advisory)

- https://security.netapp.com/advisory/ntap-20230420-0010/ (af854a3a-2127-422b-91ae-364da2661108; Third Party Advisory)

- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e)

- https://cert-portal.siemens.com/productcert/html/ssa-943925.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e)

## Provenance

- CNA: hackerone: https://www.cve.org/CVERecord?id=CVE-2023-27537; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-27537; retrieved 2026-11-03; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2023-27537; retrieved 2026-11-02; source updated Not reported

Revision: 919f7abf4c71c8012bfa68efe62ccb54f46afd5869ef924f4049f09b1d42d9a7

Canonical: https://y2.dev/cve/CVE-2023-27537

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