CVE-2026-9546 (GCVE-0-2026-9546)

Vulnerability from cvelistv5 – Published: 2026-07-03 06:18 – Updated: 2026-07-03 06:18
VLAI?
Title
sending old referer
Summary
A vulnerability in libcurl caused the HTTP `Referer:` header to persist even when explicitly cleared. While the documentation states that passing NULL to `CURLOPT_REFERER` suppresses the header, the option failed to clear the internal state. As a result the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.
Severity ?
No CVSS data available.
CWE
Assigner
References
Impacted products
Vendor Product Version
curl curl Affected: 8.20.0 , ≤ 8.20.0 (semver)
Affected: 8.19.0 , ≤ 8.19.0 (semver)
Affected: 8.18.0 , ≤ 8.18.0 (semver)
Create a notification for this product.
Credits
renjian on hackerone Daniel Stenberg
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "lessThanOrEqual": "8.20.0",
              "status": "affected",
              "version": "8.20.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.19.0",
              "status": "affected",
              "version": "8.19.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.18.0",
              "status": "affected",
              "version": "8.18.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "renjian on hackerone"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Daniel Stenberg"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "A vulnerability in libcurl caused the HTTP `Referer:` header to persist even\nwhen explicitly cleared. While the documentation states that passing NULL to\n`CURLOPT_REFERER` suppresses the header, the option failed to clear the\ninternal state. As a result the previous referrer string was erroneously\nreused and sent in subsequent requests, potentially leaking sensitive\ninformation to unintended servers."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-200 Exposure of Sensitive Information to an Unauthorized Actor",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-03T06:18:14.447Z",
        "orgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "shortName": "curl"
      },
      "references": [
        {
          "name": "json",
          "url": "https://curl.se/docs/CVE-2026-9546.json"
        },
        {
          "name": "www",
          "url": "https://curl.se/docs/CVE-2026-9546.html"
        },
        {
          "name": "issue",
          "url": "https://hackerone.com/reports/3754343"
        }
      ],
      "title": "sending old referer"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
    "assignerShortName": "curl",
    "cveId": "CVE-2026-9546",
    "datePublished": "2026-07-03T06:18:14.447Z",
    "dateReserved": "2026-05-26T06:45:18.723Z",
    "dateUpdated": "2026-07-03T06:18:14.447Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.