FKIE_CVE-2026-6276

Vulnerability from fkie_nvd - Published: 2026-05-13 13:01 - Updated: 2026-05-14 14:21
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom `Host:` header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.
References
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-6276.htmlPatch, Vendor Advisory
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-6276.jsonProduct
2499f714-1537-4658-8207-48ae4bb9eae9https://hackerone.com/reports/3671818Exploit, Issue Tracking, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/04/29/13Mailing List, Third Party Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://hackerone.com/reports/3671818Exploit, Issue Tracking, Third Party Advisory
Impacted products
Vendor Product Version
haxx curl *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "4F8139D4-8C72-4D4D-BD15-A64E8818AED1",
              "versionEndExcluding": "8.20.0",
              "versionStartIncluding": "7.71.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Using libcurl, when a custom `Host:` header is first set for an HTTP request\nand a second request is subsequently done using the same *easy handle* but\nwithout the custom `Host:` header set, the second request would use stale\ninformation and pass on cookies meant for the first host in the second\nrequest. Leak them."
    }
  ],
  "id": "CVE-2026-6276",
  "lastModified": "2026-05-14T14:21:06.997",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-13T13:01:56.800",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-6276.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Product"
      ],
      "url": "https://curl.se/docs/CVE-2026-6276.json"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3671818"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "url": "http://www.openwall.com/lists/oss-security/2026/04/29/13"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3671818"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-319"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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