FKIE_CVE-2026-9546

Vulnerability from fkie_nvd - Published: 2026-07-03 07:16 - Updated: 2026-07-03 07:16
Severity
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.
References
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-9546.html
2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-9546.json
2499f714-1537-4658-8207-48ae4bb9eae9https://hackerone.com/reports/3754343
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "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"
            }
          ]
        }
      ],
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9"
    }
  ],
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2026-9546",
  "lastModified": "2026-07-03T07:16:25.893",
  "metrics": {},
  "published": "2026-07-03T07:16:25.893",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "url": "https://curl.se/docs/CVE-2026-9546.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "url": "https://curl.se/docs/CVE-2026-9546.json"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "url": "https://hackerone.com/reports/3754343"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Received"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • 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.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • 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.