ghsa-xrv5-2wwg-jp3r
Vulnerability from github
Published
2025-07-16 15:32
Modified
2025-07-16 15:32
Severity ?
8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/R:U/V:C
Details

A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-5994"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-349"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-07-16T15:15:33Z",
    "severity": "HIGH"
  },
  "details": "A multi-vendor cache poisoning vulnerability named \u0027Rebirthday Attack\u0027 has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., \u0027--enable-subnet\u0027, AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the \u0027send-client-subnet\u0027, \u0027client-subnet-zone\u0027 or \u0027client-subnet-always-forward\u0027 options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.",
  "id": "GHSA-xrv5-2wwg-jp3r",
  "modified": "2025-07-16T15:32:33Z",
  "published": "2025-07-16T15:32:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-5994"
    },
    {
      "type": "WEB",
      "url": "https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:C/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}


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