cve-2026-9545

{
  "cvss": 7.5,
  "datePublished": "2026-07-03T07:16:25.807",
  "dateUpdated": "2026-09-15T07:16:34.947",
  "description": "In this scenario, libcurl first uses a proper HTTP/3 server for the initial\ntransfers, and when it makes a second transfer to the same site it has been\nreplaced by the attacker's impostor machine - without a valid certificate.\n\nWhen libcurl returns to the hostname the second time with a cached SSL session\n(`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the\n`CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might\nsend off the second request's bytes on that new connection *before* enforcing\nthe certificate verification failure. Potentially leaking sensitive\ninformation.",
  "id": "CVE-2026-9545",
  "raw": {
    "affected": [
      {
        "affectedData": [
          {
            "defaultStatus": "unaffected",
            "product": "curl",
            "vendor": "curl",
            "versions": [
              {
                "lessThan": "8.14.2",
                "status": "affected",
                "version": "8.11.0",
                "versionType": "semver"
              },
              {
                "lessThan": "8.16.1",
                "status": "affected",
                "version": "8.15.0",
                "versionType": "semver"
              },
              {
                "lessThan": "8.20.1",
                "status": "affected",
                "version": "8.17.0",
                "versionType": "semver"
              }
            ]
          },
          {
            "defaultStatus": "unaffected",
            "product": "curl",
            "repo": "https://github.com/curl/curl.git",
            "vendor": "curl",
            "versions": [
              {
                "lessThan": "7b9613fa9b1a5e04301a3920eef58e8138dad05e",
                "status": "affected",
                "version": "962097b8dd44ed5b9e7984bc1cdffdbdd566857f",
                "versionType": "git"
              }
            ]
          },
          {
            "defaultStatus": "unaffected",
            "product": "curl",
            "vendor": "curl",
            "versions": [
              {
                "status": "affected",
                "version": "8.20.0"
              },
              {
                "status": "affected",
                "version": "8.19.0"
              },
              {
                "status": "affected",
                "version": "8.18.0"
              },
              {
                "status": "affected",
                "version": "8.17.0"
              },
              {
                "status": "affected",
                "version": "8.16.0"
              },
              {
                "status": "affected",
                "version": "8.15.0"
              },
              {
                "status": "affected",
                "version": "8.14.1"
              },
              {
                "status": "affected",
                "version": "8.14.0"
              },
              {
                "status": "affected",
                "version": "8.13.0"
              },
              {
                "status": "affected",
                "version": "8.12.1"
              },
              {
                "status": "affected",
                "version": "8.12.0"
              },
              {
                "status": "affected",
                "version": "8.11.1"
              },
              {
                "status": "affected",
                "version": "8.11.0"
              }
            ]
          }
        ],
        "source": "2499f714-1537-4658-8207-48ae4bb9eae9"
      }
    ],
    "configurations": [
      {
        "nodes": [
          {
            "cpeMatch": [
              {
                "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
                "matchCriteriaId": "C6D1007D-3E09-4D44-993A-9ACC2316FD0A",
                "versionEndExcluding": "8.21.0",
                "versionStartIncluding": "8.11.0",
                "vulnerable": true
              }
            ],
            "negate": false,
            "operator": "OR"
          }
        ]
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "In this scenario, libcurl first uses a proper HTTP/3 server for the initial\ntransfers, and when it makes a second transfer to the same site it has been\nreplaced by the attacker's impostor machine - without a valid certificate.\n\nWhen libcurl returns to the hostname the second time with a cached SSL session\n(`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the\n`CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might\nsend off the second request's bytes on that new connection *before* enforcing\nthe certificate verification failure. Potentially leaking sensitive\ninformation."
      }
    ],
    "id": "CVE-2026-9545",
    "lastModified": "2026-09-15T07:16:34.947",
    "metrics": {
      "cvssMetricV31": [
        {
          "cvssData": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "exploitabilityScore": 3.9,
          "impactScore": 3.6,
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-9545",
            "options": [
              {
                "exploitation": "poc"
              },
              {
                "automatable": "yes"
              },
              {
                "technicalImpact": "partial"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-07-06T16:52:42.898546Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-07-03T07:16:25.807",
    "references": [
      {
        "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "tags": [
          "Patch",
          "Vendor Advisory"
        ],
        "url": "https://curl.se/docs/CVE-2026-9545.html"
      },
      {
        "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "tags": [
          "Vendor Advisory"
        ],
        "url": "https://curl.se/docs/CVE-2026-9545.json"
      },
      {
        "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "tags": [
          "Exploit",
          "Issue Tracking",
          "Third Party Advisory"
        ],
        "url": "https://hackerone.com/reports/3752888"
      },
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "tags": [
          "Exploit",
          "Issue Tracking",
          "Third Party Advisory"
        ],
        "url": "https://hackerone.com/reports/3752888"
      }
    ],
    "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
    "vulnStatus": "Modified",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-200"
          }
        ],
        "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "type": "Secondary"
      },
      {
        "description": [
          {
            "lang": "en",
            "value": "NVD-CWE-noinfo"
          }
        ],
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "severity": "HIGH",
  "source": "nvd",
  "title": "In this scenario, libcurl first uses a proper HTTP/3 server for the initial\ntransfers, and when it makes a second tra..."
}