CVE-2026-42960 (GCVE-0-2026-42960)
Vulnerability from cvelistv5
Published
2026-05-20 09:21
Modified
2026-05-20 13:04
CWE
  • CWE-349 - Acceptance of Extraneous Untrusted Data With Trusted Data
Summary
NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.
Impacted products
Vendor Product Version
NLnet Labs Unbound Version: 0   
Create a notification for this product.
Show details on NVD website


{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42960",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-20T13:04:22.642063Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-20T13:04:34.933Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
            {
              "lessThan": "1.25.1",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "TaoFei Guo (Peking University)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Yang Luo (Tsinghua University)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "JianJun Chen (Tsinghua University)"
        }
      ],
      "datePublic": "2026-05-20T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound\u0027s cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "baseScore": 5.7,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H/E:P/U:Amber",
            "version": "4.0"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-349",
              "description": "CWE-349: Acceptance of Extraneous Untrusted Data With Trusted Data",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-20T09:21:02.070Z",
        "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "shortName": "NLnet Labs"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42960.txt"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "This issue is fixed starting with version 1.25.1"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2025-11-28T00:00:00.000Z",
          "value": "Issue reported by TaoFei Guo"
        },
        {
          "lang": "en",
          "time": "2025-11-28T00:00:00.000Z",
          "value": "NLnet Labs acknowledges the report"
        },
        {
          "lang": "en",
          "time": "2025-12-22T00:00:00.000Z",
          "value": "NLnet Labs shares a patch"
        },
        {
          "lang": "en",
          "time": "2026-03-16T00:00:00.000Z",
          "value": "TaoFei Guo verifies patch"
        },
        {
          "lang": "en",
          "time": "2026-05-20T00:00:00.000Z",
          "value": "Fixes released with version 1.25.1"
        }
      ],
      "title": "Possible cache poisoning via promiscuous records for the authority section",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
    "assignerShortName": "NLnet Labs",
    "cveId": "CVE-2026-42960",
    "datePublished": "2026-05-20T09:21:02.070Z",
    "dateReserved": "2026-05-07T10:13:43.999Z",
    "dateUpdated": "2026-05-20T13:04:34.933Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.


Loading…

Loading…