Vulnerability-Lookup

GHSA-FX8Q-9CM5-75V9

Vulnerability from github – Published: 2026-05-20 12:30 – Updated: 2026-05-21 00:30

Details

NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code.

Severity ?

5.9 (Medium)


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

4.6 (Medium)


                  
                    CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

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{
  "affected": [],
  "aliases": [
    "CVE-2026-44608"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-413"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-20T10:16:28Z",
    "severity": "MODERATE"
  },
  "details": "NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with \u0027rpz-nsip\u0027/\u0027rpz-nsdname\u0027 triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with \u0027rpz-nsip\u0027/\u0027rpz-nsdname\u0027 triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code.",
  "id": "GHSA-fx8q-9cm5-75v9",
  "modified": "2026-05-21T00:30:27Z",
  "published": "2026-05-20T12:30:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44608"
    },
    {
      "type": "WEB",
      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44608.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-44608 (GCVE-0-2026-44608)

Vulnerability from cvelistv5 – Published: 2026-05-20 09:21 – Updated: 2026-05-20 12:54

Title

Use after free and crash under special conditions in RPZ code

Summary

Severity ?

4.6 (Medium)


                        
                          CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

CWE

CWE-413 - Improper Resource Locking

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: 1.14.0 , < 1.25.1 (semver)

Date Public ?

2026-05-20 00:00

Credits

Qifan Zhang (Palo Alto Networks)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-44608",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-20T12:46:59.939210Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
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          "vendor": "NLnet Labs",
          "versions": [
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              "versionType": "semver"
            }
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          "type": "finder",
          "value": "Qifan Zhang (Palo Alto Networks)"
        }
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      "datePublic": "2026-05-20T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with \u0027rpz-nsip\u0027/\u0027rpz-nsdname\u0027 triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with \u0027rpz-nsip\u0027/\u0027rpz-nsdname\u0027 triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code."
        }
      ],
      "metrics": [
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            "version": "4.0"
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          "scenarios": [
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          "descriptions": [
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          ]
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      "providerMetadata": {
        "dateUpdated": "2026-05-20T09:21:57.360Z",
        "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "shortName": "NLnet Labs"
      },
      "references": [
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          "lang": "en",
          "value": "This issue is fixed starting with version 1.25.1"
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          "time": "2026-05-07T00:00:00.000Z",
          "value": "NLnet Labs shares patch"
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          "lang": "en",
          "time": "2026-05-08T00:00:00.000Z",
          "value": "Qifan Zhang verifies patch"
        },
        {
          "lang": "en",
          "time": "2026-05-20T00:00:00.000Z",
          "value": "Fixes released with version 1.25.1"
        }
      ],
      "title": "Use after free and crash under special conditions in RPZ code",
      "x_generator": {
        "engine": "cvelib 1.8.0"
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  },
  "cveMetadata": {
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    "datePublished": "2026-05-20T09:21:57.360Z",
    "dateReserved": "2026-05-07T10:07:51.822Z",
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    "state": "PUBLISHED"
  },
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  "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.

Action not permitted

GHSA-FX8Q-9CM5-75V9

CVE-2026-44608 (GCVE-0-2026-44608)

Tags

Sightings

Nomenclature