{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55973",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-22T14:05:39.964116Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-22T14:06:00.025Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
            {
              "lessThan": "1.25.2",
              "status": "affected",
              "version": "1.23.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Qifan Zhang (Palo Alto Networks)"
        }
      ],
      "datePublic": "2026-07-22T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when \u0027dns-error-reporting: yes\u0027 is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option\u0027s length as the length of the agent domain. When a domain name check is performed on the agent domain, the returned lenght is not used and if the agent domain is followed by garbage, those bytes are moved onto the tail of the synthetic \u0027_er.\u0027 report query name. That query name is later used in the iterator via a subquery to send out the DNS Error Report and when Unbound tries to walk that query name during \u0027find_closest_of_type()\u0027, it strips labels using the query name length rather than stopping at the embedded root, walks one byte past it, and feeds the first garbage byte to \u0027dname_query_hash()\u0027 as a label length writing over the stack variable \u0027labuf\u0027. One ordinary upstream response from a delegated zone the attacker controls is sufficient to terminate the daemon."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "\u0027dns-error-reporting: yes\u0027"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20: Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-22T13:09:50.942Z",
        "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "shortName": "NLnet Labs"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-55973.txt"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "This issue is fixed starting with version 1.25.2"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2026-05-04T00:00:00.000Z",
          "value": "Issue reported by Qifan Zhang"
        },
        {
          "lang": "en",
          "time": "2026-05-29T00:00:00.000Z",
          "value": "NLnet Labs shares patch"
        },
        {
          "lang": "en",
          "time": "2026-05-30T00:00:00.000Z",
          "value": "Qifan Zhang verifies patch"
        },
        {
          "lang": "en",
          "time": "2026-07-22T00:00:00.000Z",
          "value": "Fixes released with version 1.25.2"
        }
      ],
      "title": "\u0027dns-error-reporting: yes\u0027 leads to stack buffer overflow",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
    "assignerShortName": "NLnet Labs",
    "cveId": "CVE-2026-55973",
    "datePublished": "2026-07-22T13:09:50.942Z",
    "dateReserved": "2026-06-22T12:27:22.820Z",
    "dateUpdated": "2026-07-22T14:06:00.025Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-55973\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-07-22T14:05:39.964116Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-07-22T14:05:54.165Z\"}}], \"cna\": {\"title\": \"\u0027dns-error-reporting: yes\u0027 leads to stack buffer overflow\", \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Qifan Zhang (Palo Alto Networks)\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 7.5, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"\u0027dns-error-reporting: yes\u0027\"}]}], \"affected\": [{\"vendor\": \"NLnet Labs\", \"product\": \"Unbound\", \"versions\": [{\"status\": \"affected\", \"version\": \"1.23.0\", \"lessThan\": \"1.25.2\", \"versionType\": \"semver\"}], \"defaultStatus\": \"unaffected\"}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-05-04T00:00:00.000Z\", \"value\": \"Issue reported by Qifan Zhang\"}, {\"lang\": \"en\", \"time\": \"2026-05-29T00:00:00.000Z\", \"value\": \"NLnet Labs shares patch\"}, {\"lang\": \"en\", \"time\": \"2026-05-30T00:00:00.000Z\", \"value\": \"Qifan Zhang verifies patch\"}, {\"lang\": \"en\", \"time\": \"2026-07-22T00:00:00.000Z\", \"value\": \"Fixes released with version 1.25.2\"}], \"solutions\": [{\"lang\": \"en\", \"value\": \"This issue is fixed starting with version 1.25.2\"}], \"datePublic\": \"2026-07-22T00:00:00.000Z\", \"references\": [{\"url\": \"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-55973.txt\", \"tags\": [\"vendor-advisory\"]}], \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when \u0027dns-error-reporting: yes\u0027 is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option\u0027s length as the length of the agent domain. When a domain name check is performed on the agent domain, the returned lenght is not used and if the agent domain is followed by garbage, those bytes are moved onto the tail of the synthetic \u0027_er.\u0027 report query name. That query name is later used in the iterator via a subquery to send out the DNS Error Report and when Unbound tries to walk that query name during \u0027find_closest_of_type()\u0027, it strips labels using the query name length rather than stopping at the embedded root, walks one byte past it, and feeds the first garbage byte to \u0027dname_query_hash()\u0027 as a label length writing over the stack variable \u0027labuf\u0027. One ordinary upstream response from a delegated zone the attacker controls is sufficient to terminate the daemon.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-20\", \"description\": \"CWE-20: Improper Input Validation\"}]}], \"providerMetadata\": {\"orgId\": \"206fc3a0-e175-490b-9eaa-a5738056c9f6\", \"shortName\": \"NLnet Labs\", \"dateUpdated\": \"2026-07-22T13:09:50.942Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-55973\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-22T14:06:00.025Z\", \"dateReserved\": \"2026-06-22T12:27:22.820Z\", \"assignerOrgId\": \"206fc3a0-e175-490b-9eaa-a5738056c9f6\", \"datePublished\": \"2026-07-22T13:09:50.942Z\", \"assignerShortName\": \"NLnet Labs\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}