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GHSA-3HPW-4MFR-9F85

Vulnerability from github – Published: 2026-09-06 18:34 – Updated: 2026-09-08 21:33
VLAI
Details

When libpsl support is enabled, libcurl fails to enforce the Public Suffix List boundary check when processing a Set-Cookie header where the Domain attribute explicitly matches an origin host that is itself a public suffix (e.g., Domain=co.uk set by co.uk).

Instead of coercing it into a strict host-only cookie, libcurl saves the cookie with wildcard domain scope (.co.uk). Consequently, the cookie is inappropriately included in subsequent outbound requests or HTTP redirects to arbitrary sibling subdomains under the same public suffix (e.g., attacker.co.uk).

Severity
8.2 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
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{
  "affected": [],
  "aliases": [
    "CVE-2026-82209"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-201"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-06T18:17:22Z",
    "severity": "HIGH"
  },
  "details": "When libpsl support is enabled, libcurl fails to enforce the Public Suffix\nList boundary check when processing a `Set-Cookie` header where the `Domain`\nattribute explicitly matches an origin host that is itself a public suffix\n(e.g., `Domain=co.uk` set by `co.uk`).\n\nInstead of coercing it into a strict host-only cookie, libcurl saves the\ncookie with wildcard domain scope (`.co.uk`). Consequently, the cookie is\ninappropriately included in subsequent outbound requests or HTTP redirects to\narbitrary sibling subdomains under the same public suffix (e.g.,\n`attacker.co.uk`).",
  "id": "GHSA-3hpw-4mfr-9f85",
  "modified": "2026-09-08T21:33:03Z",
  "published": "2026-09-06T18:34:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82209"
    },
    {
      "type": "WEB",
      "url": "https://hackerone.com/reports/3972385"
    },
    {
      "type": "WEB",
      "url": "https://curl.se/docs/CVE-2026-82209.html"
    },
    {
      "type": "WEB",
      "url": "https://curl.se/docs/CVE-2026-82209.json"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}



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