UBUNTU-CVE-2026-40622 (CVE-2026-40622)

Vulnerability from osv_ubuntu – Published: 2026-05-20 00:00 – Updated: 2026-06-02 19:39 – Source website
VLAI
Details

NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.

Severity
6.6 (Medium)
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:U/U:Amber
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libunbound2",
            "binary_version": "1.5.8-1ubuntu1.1+esm3"
          },
          {
            "binary_name": "python-unbound",
            "binary_version": "1.5.8-1ubuntu1.1+esm3"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.5.8-1ubuntu1.1+esm3"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.5.8-1ubuntu1.1+esm3"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.5.8-1ubuntu1.1+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.5.8-1ubuntu1.1+esm3?arch=source\u0026distro=esm-infra-legacy/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.4.22-1ubuntu6",
        "1.5.7-1ubuntu1",
        "1.5.7-1ubuntu2",
        "1.5.8-1ubuntu1",
        "1.5.8-1ubuntu1.1",
        "1.5.8-1ubuntu1.1+esm1",
        "1.5.8-1ubuntu1.1+esm2",
        "1.5.8-1ubuntu1.1+esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libunbound8",
            "binary_version": "1.19.2-1ubuntu3.8"
          },
          {
            "binary_name": "python3-unbound",
            "binary_version": "1.19.2-1ubuntu3.8"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.19.2-1ubuntu3.8"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.19.2-1ubuntu3.8"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.19.2-1ubuntu3.8"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.19.2-1ubuntu3.8?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.19.2-1ubuntu3.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.17.1-2",
        "1.18.0-2ubuntu1",
        "1.18.0-2ubuntu2",
        "1.19.1-1ubuntu1",
        "1.19.2-1ubuntu1",
        "1.19.2-1ubuntu3",
        "1.19.2-1ubuntu3.1",
        "1.19.2-1ubuntu3.2",
        "1.19.2-1ubuntu3.3",
        "1.19.2-1ubuntu3.4",
        "1.19.2-1ubuntu3.5",
        "1.19.2-1ubuntu3.6",
        "1.19.2-1ubuntu3.7"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libunbound8",
            "binary_version": "1.22.0-2ubuntu2.3"
          },
          {
            "binary_name": "python3-unbound",
            "binary_version": "1.22.0-2ubuntu2.3"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.22.0-2ubuntu2.3"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.22.0-2ubuntu2.3"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.22.0-2ubuntu2.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.22.0-2ubuntu2.3?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.22.0-2ubuntu2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.22.0-1ubuntu1",
        "1.22.0-2ubuntu1",
        "1.22.0-2ubuntu2",
        "1.22.0-2ubuntu2.1",
        "1.22.0-2ubuntu2.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libunbound8",
            "binary_version": "1.24.2-1ubuntu2.1"
          },
          {
            "binary_name": "python3-unbound",
            "binary_version": "1.24.2-1ubuntu2.1"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.24.2-1ubuntu2.1"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.24.2-1ubuntu2.1"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.24.2-1ubuntu2.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.24.2-1ubuntu2.1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.24.2-1ubuntu2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.22.0-2ubuntu2",
        "1.22.0-2ubuntu4",
        "1.24.2-1ubuntu1",
        "1.24.2-1ubuntu2"
      ]
    }
  ],
  "aliases": [],
  "details": "NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the \u0027ghost domain names\u0027 family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other \u0027ghost domain names\u0027 attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value (\u0027cache-max-ttl\u0027). In configurations where \u0027harden-referral-path: yes\u0027 is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.",
  "id": "UBUNTU-CVE-2026-40622",
  "modified": "2026-06-02T19:39:29Z",
  "published": "2026-05-20T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-40622"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-40622"
    },
    {
      "type": "REPORT",
      "url": "https://nlnetlabs.nl/news/2026/May/20/unbound-1.25.1-released/"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8282-1"
    }
  ],
  "related": [
    "USN-8282-1"
  ],
  "schema_version": "1.7.0",
  "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:U/U:Amber",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-40622"
  ]
}



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