Vulnerability-Lookup

ubuntu-cve-2026-50243

Vulnerability from osv_ubuntu

Published

2026-07-22 14:17

Modified

2026-07-29 07:58

Summary

Details

In NLnet Labs Unbound 1.6.2 up to and including 1.25.1, when Unbound is configured with the 'respip' module in front of the validator together with a 'response-ip' redirect rule or an RPZ file with an RPZ-IP trigger, the rewriting handler does not check the security status of the upstream answer and can instead rewrite a BOGUS A/AAAA answer to point to an operator's configured IP. If the validator finds an expired or otherwise invalid RRSIG on an answer whose A record falls within a 'response-ip'/RPZ configuration, the answer is still rewritten and given a hard coded security level of INSECURE. This results in the client receiving an INSECURE NOERROR reply rewritten by the operator's configured IP. A malicious actor can exploit the possible poisonous effect by spoofing a BOGUS A/AAAA answer that falls inside the operator's configured subnet rewrites. Such DNSSEC protected answers are then insecurely redirected to the operator's configured target.

Severity

6.3 (Medium)


                    
                      CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

3.7 (Low)


                    
                      CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-50243	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-50243	REPORT
	https://community.nlnetlabs.nl/t/unbound-1-25-2-r…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libunbound2",
            "binary_version": "1.4.22-1ubuntu4.14.04.3+esm3"
          },
          {
            "binary_name": "python-unbound",
            "binary_version": "1.4.22-1ubuntu4.14.04.3+esm3"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.4.22-1ubuntu4.14.04.3+esm3"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.4.22-1ubuntu4.14.04.3+esm3"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.4.22-1ubuntu4.14.04.3+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.4.22-1ubuntu4.14.04.3+esm3?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
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        "1.4.21-1",
        "1.4.21-1ubuntu1",
        "1.4.21-1ubuntu2",
        "1.4.22-1ubuntu1",
        "1.4.22-1ubuntu2",
        "1.4.22-1ubuntu3",
        "1.4.22-1ubuntu4",
        "1.4.22-1ubuntu4.14.04.1",
        "1.4.22-1ubuntu4.14.04.2",
        "1.4.22-1ubuntu4.14.04.3",
        "1.4.22-1ubuntu4.14.04.3+esm1",
        "1.4.22-1ubuntu4.14.04.3+esm2",
        "1.4.22-1ubuntu4.14.04.3+esm3"
      ]
    },
    {
      "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"
        }
      ],
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        "1.5.7-1ubuntu1",
        "1.5.7-1ubuntu2",
        "1.5.8-1ubuntu1",
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        "1.5.8-1ubuntu1.1+esm1",
        "1.5.8-1ubuntu1.1+esm2",
        "1.5.8-1ubuntu1.1+esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libunbound2",
            "binary_version": "1.6.7-1ubuntu2.6+esm4"
          },
          {
            "binary_name": "python-unbound",
            "binary_version": "1.6.7-1ubuntu2.6+esm4"
          },
          {
            "binary_name": "python3-unbound",
            "binary_version": "1.6.7-1ubuntu2.6+esm4"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.6.7-1ubuntu2.6+esm4"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.6.7-1ubuntu2.6+esm4"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.6.7-1ubuntu2.6+esm4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.6.7-1ubuntu2.6+esm4?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
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        "1.6.7-1",
        "1.6.7-1build1",
        "1.6.7-1ubuntu1",
        "1.6.7-1ubuntu2",
        "1.6.7-1ubuntu2.1",
        "1.6.7-1ubuntu2.2",
        "1.6.7-1ubuntu2.3",
        "1.6.7-1ubuntu2.4",
        "1.6.7-1ubuntu2.5",
        "1.6.7-1ubuntu2.6",
        "1.6.7-1ubuntu2.6+esm2",
        "1.6.7-1ubuntu2.6+esm3",
        "1.6.7-1ubuntu2.6+esm4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libunbound8",
            "binary_version": "1.9.4-2ubuntu1.11+esm1"
          },
          {
            "binary_name": "python-unbound",
            "binary_version": "1.9.4-2ubuntu1.11+esm1"
          },
          {
            "binary_name": "python3-unbound",
            "binary_version": "1.9.4-2ubuntu1.11+esm1"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.9.4-2ubuntu1.11+esm1"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.9.4-2ubuntu1.11+esm1"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.9.4-2ubuntu1.11+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.9.4-2ubuntu1.11+esm1?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.9.0-2ubuntu1",
        "1.9.0-2ubuntu2",
        "1.9.4-2",
        "1.9.4-2ubuntu1",
        "1.9.4-2ubuntu1.1",
        "1.9.4-2ubuntu1.2",
        "1.9.4-2ubuntu1.3",
        "1.9.4-2ubuntu1.4",
        "1.9.4-2ubuntu1.5",
        "1.9.4-2ubuntu1.6",
        "1.9.4-2ubuntu1.8",
        "1.9.4-2ubuntu1.9",
        "1.9.4-2ubuntu1.11",
        "1.9.4-2ubuntu1.11+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libunbound8",
            "binary_version": "1.13.1-1ubuntu5.15"
          },
          {
            "binary_name": "python3-unbound",
            "binary_version": "1.13.1-1ubuntu5.15"
          },
          {
            "binary_name": "unbound",
            "binary_version": "1.13.1-1ubuntu5.15"
          },
          {
            "binary_name": "unbound-anchor",
            "binary_version": "1.13.1-1ubuntu5.15"
          },
          {
            "binary_name": "unbound-host",
            "binary_version": "1.13.1-1ubuntu5.15"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "unbound",
        "purl": "pkg:deb/ubuntu/unbound@1.13.1-1ubuntu5.15?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.13.1-1ubuntu1",
        "1.13.1-1ubuntu3",
        "1.13.1-1ubuntu5",
        "1.13.1-1ubuntu5.1",
        "1.13.1-1ubuntu5.2",
        "1.13.1-1ubuntu5.3",
        "1.13.1-1ubuntu5.4",
        "1.13.1-1ubuntu5.5",
        "1.13.1-1ubuntu5.7",
        "1.13.1-1ubuntu5.8",
        "1.13.1-1ubuntu5.10",
        "1.13.1-1ubuntu5.11",
        "1.13.1-1ubuntu5.12",
        "1.13.1-1ubuntu5.13",
        "1.13.1-1ubuntu5.14",
        "1.13.1-1ubuntu5.15"
      ]
    },
    {
      "ecosystem_specific": {
        "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"
            }
          ],
          "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",
        "1.19.2-1ubuntu3.8"
      ]
    },
    {
      "ecosystem_specific": {
        "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"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.22.0-2ubuntu2",
        "1.22.0-2ubuntu4",
        "1.24.2-1ubuntu1",
        "1.24.2-1ubuntu2",
        "1.24.2-1ubuntu2.1"
      ]
    }
  ],
  "aliases": [],
  "details": "In NLnet Labs Unbound 1.6.2 up to and including 1.25.1, when Unbound is configured with the \u0027respip\u0027 module in front of the validator together with a \u0027response-ip\u0027 redirect rule or an RPZ file with an RPZ-IP trigger, the rewriting handler does not check the security status of the upstream answer and can instead rewrite a BOGUS A/AAAA answer to point to an operator\u0027s configured IP. If the validator finds an expired or otherwise invalid RRSIG on an answer whose A record falls within a \u0027response-ip\u0027/RPZ configuration, the answer is still rewritten and given a hard coded security level of INSECURE. This results in the client receiving an INSECURE NOERROR reply rewritten by the operator\u0027s configured IP. A malicious actor can exploit the possible poisonous effect by spoofing a BOGUS A/AAAA answer that falls inside the operator\u0027s configured subnet rewrites. Such DNSSEC protected answers are then insecurely redirected to the operator\u0027s configured target.",
  "id": "UBUNTU-CVE-2026-50243",
  "modified": "2026-07-29T07:58:08Z",
  "published": "2026-07-22T14:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-50243"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-50243"
    },
    {
      "type": "REPORT",
      "url": "https://community.nlnetlabs.nl/t/unbound-1-25-2-released/3430"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-50243"
  ]
}

CVE-2026-50243 (GCVE-0-2026-50243)

Vulnerability from cvelistv5 – Published: 2026-07-22 13:08 – Updated: 2026-07-22 18:58

Title

'response-ip'/'rpz' can rewrite BOGUS answers instead of returning SERVFAIL

Summary

Severity

6.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-348 - Use of Less Trusted Source

Assigner

NLnet Labs

References

1 reference

URL	Tags
https://www.nlnetlabs.nl/downloads/unbound/CVE-20…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
NLnet Labs	Unbound	Affected: 1.6.2 , < 1.25.2 (semver)

Date Public

2026-07-22 00:00

Credits

Qifan Zhang (Palo Alto Networks)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-50243",
                "options": [
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                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-22T18:57:49.710450Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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      }
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      "descriptions": [
        {
          "lang": "en",
          "value": "In NLnet Labs Unbound 1.6.2 up to and including 1.25.1, when Unbound is configured with the \u0027respip\u0027 module in front of the validator together with a \u0027response-ip\u0027 redirect rule or an RPZ file with an RPZ-IP trigger, the rewriting handler does not check the security status of the upstream answer and can instead rewrite a BOGUS A/AAAA answer to point to an operator\u0027s configured IP. If the validator finds an expired or otherwise invalid RRSIG on an answer whose A record falls within a \u0027response-ip\u0027/RPZ configuration, the answer is still rewritten and given a hard coded security level of INSECURE. This results in the client receiving an INSECURE NOERROR reply rewritten by the operator\u0027s configured IP. A malicious actor can exploit the possible poisonous effect by spoofing a BOGUS A/AAAA answer that falls inside the operator\u0027s configured subnet rewrites. Such DNSSEC protected answers are then insecurely redirected to the operator\u0027s configured target."
        }
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              "description": "CWE-348: Use of Less Trusted Source",
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        "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
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          "value": "Issue reported by Qifan Zhang"
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          "time": "2026-06-08T00:00:00.000Z",
          "value": "NLnet Labs shares patch"
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          "lang": "en",
          "time": "2026-06-11T00:00:00.000Z",
          "value": "Qifan Zhang verifies patch"
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        {
          "lang": "en",
          "time": "2026-07-22T00:00:00.000Z",
          "value": "Fixes released with version 1.25.2"
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      ],
      "title": "\u0027response-ip\u0027/\u0027rpz\u0027 can rewrite BOGUS answers instead of returning SERVFAIL",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
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    "assignerShortName": "NLnet Labs",
    "cveId": "CVE-2026-50243",
    "datePublished": "2026-07-22T13:08:21.443Z",
    "dateReserved": "2026-06-22T12:27:22.796Z",
    "dateUpdated": "2026-07-22T18:58:00.043Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

ubuntu-cve-2026-50243

Vulnerability from osv_ubuntu

CVE-2026-50243 (GCVE-0-2026-50243)

Tags

Sightings

Nomenclature