Vulnerability-Lookup

GHSA-2PWM-327C-RQ4R

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

Details

In NLnet Labs Unbound 1.16.2 up to and including 1.25.1, a similar vulnerability as with CVE-2026-40622 in the 'ghost domain names' family of attacks was found in Unbound that could extend the ghost domain window by up to one cached TTL configured value for A/AAAA glue records. 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 A/AAAA query can cause Unbound to overwrite the cached expired parent-side glue 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 query is required since Unbound implicitly performs that query. This is a variant of CVE-2026-40622 which only addressed the NS query.

Severity

3.7 (Low)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-42955"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-672"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-22T14:17:18Z",
    "severity": "LOW"
  },
  "details": "In NLnet Labs Unbound 1.16.2 up to and including 1.25.1, a similar vulnerability as with CVE-2026-40622 in the \u0027ghost domain names\u0027 family of attacks was found in Unbound that could extend the ghost domain window by up to one cached TTL configured value for A/AAAA glue records. 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 A/AAAA query can cause Unbound to overwrite the cached expired parent-side glue 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 query is required since Unbound implicitly performs that query. This is a variant of CVE-2026-40622 which only addressed the NS query.",
  "id": "GHSA-2pwm-327c-rq4r",
  "modified": "2026-07-22T15:31:24Z",
  "published": "2026-07-22T15:31:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42955"
    },
    {
      "type": "WEB",
      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42955.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-42955 (GCVE-0-2026-42955)

Vulnerability from cvelistv5 – Published: 2026-07-22 13:05 – Updated: 2026-07-22 14:26

Title

Extra fix for CVE-2026-40622 to also clamp the TTL of A/AAAA records disallowing a one-time 'ghost domain' delegation renewal via glue records

Summary

Severity

3.7 (Low)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-672 - Operation on a Resource after Expiration or Release

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: 1.16.2 , < 1.25.2 (semver)

Date Public

2026-07-22 00:00

Credits

Qifan Zhang (Palo Alto Networks)

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42955",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-22T14:26:22.407643Z",
                "version": "2.0.3"
              },
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
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          "defaultStatus": "unaffected",
          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
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      "descriptions": [
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          "lang": "en",
          "value": "In NLnet Labs Unbound 1.16.2 up to and including 1.25.1, a similar vulnerability as with CVE-2026-40622 in the \u0027ghost domain names\u0027 family of attacks was found in Unbound that could extend the ghost domain window by up to one cached TTL configured value for A/AAAA glue records. 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 A/AAAA query can cause Unbound to overwrite the cached expired parent-side glue 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 query is required since Unbound implicitly performs that query. This is a variant of CVE-2026-40622 which only addressed the NS query."
        }
      ],
      "metrics": [
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          "value": "Issue reported by Qifan Zhang"
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          "time": "2026-06-10T00:00:00.000Z",
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          "time": "2026-06-13T00:00:00.000Z",
          "value": "Qifan Zhang verifies patch"
        },
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          "time": "2026-07-22T00:00:00.000Z",
          "value": "Fixes released with version 1.25.2"
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      ],
      "title": "Extra fix for CVE-2026-40622 to also clamp the TTL of A/AAAA records disallowing a one-time \u0027ghost domain\u0027 delegation renewal via glue records",
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  "cveMetadata": {
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    "datePublished": "2026-07-22T13:05:53.695Z",
    "dateReserved": "2026-06-22T10:11:10.510Z",
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}

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.

Action not permitted

GHSA-2PWM-327C-RQ4R

CVE-2026-42955 (GCVE-0-2026-42955)

Tags

Sightings

Nomenclature