Vulnerability-Lookup

CVE-2026-50046 (GCVE-0-2026-50046)

Vulnerability from cvelistv5 – Published: 2026-07-22 13:08 – Updated: 2026-07-22 18:57

Title

Possible heap use-after-free in an error path when a DoT forwarded query is jostled out

Summary

In NLnet Labs Unbound 1.15.0 up to and including 1.25.1, the TLS server name used for DNS-over-TLS (DoT) forwarded queries is tied to a struct's ('serviced_query') lifetime but also referenced by another struct ('waiting_tcp'). When the owning struct is jostled out of the mesh while the DoT TCP stream is still handshaking it frees the storage behind the referenced string and if the TLS stream then errors out, it dereferences the freed pointer. The dereference is read-only and the practical impact is a daemon crash resulting in denial of service. A malicious actor that knows a DoT forwarding/stub Unbound's configuration could exploit the vulnerability by quering records in the appropriate zone while keeping Unbound uder pressure so that the jostle logic kicks in. If answers for the vulnerable zone are slow, the likelihood of jostling such queries is higher, although the timing of the jostle needs to be precise. Requirements for a vulnerable Unbound is the existence of a stub/forward zone configured for DoT together with a configured '#authname' suffix on the server identification. The connectivity to the server needs to exhibit a transient failure at the correct time in order to kick off the vulnerable error path.

Severity

5.9 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-416 - Use After Free

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: 1.15.0 , < 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

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FKIE_CVE-2026-50046

Vulnerability from fkie_nvd - Published: 2026-07-22 14:17 - Updated: 2026-07-22 20:33

Severity

5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	sep@nlnetlabs.nl	https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50046.txt

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
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              "lessThan": "1.25.2",
              "status": "affected",
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    }
  ],
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  "lastModified": "2026-07-22T20:33:11.590",
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GHSA-FG9V-M7XF-P865

Vulnerability from github – Published: 2026-07-22 15:31 – Updated: 2026-07-22 15:31

Details

Severity

5.9 (Medium)


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

Show details on source website

JSON

To clipboard

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  "affected": [],
  "aliases": [
    "CVE-2026-50046"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
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  "id": "GHSA-fg9v-m7xf-p865",
  "modified": "2026-07-22T15:31:24Z",
  "published": "2026-07-22T15:31:24Z",
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      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50046"
    },
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      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50046.txt"
    }
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}

MSRC_CVE-2026-50046

Vulnerability from csaf_microsoft - Published: 2026-07-23 01:04 - Updated: 2026-07-23 01:04

Summary

Possible heap use-after-free in an error path when a DoT forwarded query is jostled out

Notes

Additional Resources: To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

Disclaimer: The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

CVE-2026-50046

5.9 (Medium)


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

CWE-416 - Use After Free

Affected products

Known affected 1 product

Product	Identifier	Version	Remediation
Unresolved product id: 17084-1		—	None Available

References

4 references

URL	Category
https://msrc.microsoft.com/csaf/vex/2026/msrc_cve…	self
https://support.microsoft.com/lifecycle	external
https://www.first.org/cvss	external
https://msrc.microsoft.com/csaf/vex/2026/msrc_cve…	self

JSON

To clipboard

{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
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      "tlp": {
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        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
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    ],
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      "contact_details": "secure@microsoft.com",
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      {
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        "summary": "CVE-2026-50046 Possible heap use-after-free in an error path when a DoT forwarded query is jostled out - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-50046.json"
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        "summary": "Microsoft Support Lifecycle",
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      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "Possible heap use-after-free in an error path when a DoT forwarded query is jostled out",
    "tracking": {
      "current_release_date": "2026-07-23T01:04:51.000Z",
      "generator": {
        "date": "2026-07-23T07:19:41.831Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-50046",
      "initial_release_date": "2026-07-23T01:04:51.000Z",
      "revision_history": [
        {
          "date": "2026-07-23T01:04:51.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "azl3 unbound 0:1.25.1-1.azl3",
                "product": {
                  "name": "azl3 unbound 0:1.25.1-1.azl3",
                  "product_id": "1"
                }
              }
            ],
            "category": "product_name",
            "name": "unbound"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 unbound 0:1.25.1-1.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-50046",
      "cwe": {
        "id": "CWE-416",
        "name": "Use After Free"
      },
      "notes": [
        {
          "category": "general",
          "text": "NLnet Labs",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "known_affected": [
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-50046 Possible heap use-after-free in an error path when a DoT forwarded query is jostled out - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-50046.json"
        }
      ],
      "remediations": [
        {
          "category": "none_available",
          "date": "2026-07-23T01:04:51.000Z",
          "details": "There is no fix available for this vulnerability as of now",
          "product_ids": [
            "17084-1"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "environmentalScore": 0.0,
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "temporalScore": 5.9,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "products": [
            "17084-1"
          ]
        }
      ],
      "title": "Possible heap use-after-free in an error path when a DoT forwarded query is jostled out"
    }
  ]
}

ubuntu-cve-2026-50046

Vulnerability from osv_ubuntu

Published

2026-07-23 00:00

Modified

2026-07-23 00:00

Summary

Details

(In NLnet Labs Unbound 1.15.0 up to and including 1.25.1, the TLS serve ...)

Severity

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-50046	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-50046	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": [
        "1.4.20-1",
        "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"
        }
      ],
      "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": {
        "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": [
        "1.6.5-1",
        "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 1.15.0 up to and including 1.25.1, the TLS serve ...)",
  "id": "UBUNTU-CVE-2026-50046",
  "modified": "2026-07-23T00:00:00Z",
  "published": "2026-07-23T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-50046"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-50046"
    },
    {
      "type": "REPORT",
      "url": "https://community.nlnetlabs.nl/t/unbound-1-25-2-released/3430"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-50046"
  ]
}

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

CVE-2026-50046 (GCVE-0-2026-50046)

FKIE_CVE-2026-50046

GHSA-FG9V-M7XF-P865

MSRC_CVE-2026-50046

ubuntu-cve-2026-50046

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature