FKIE_CVE-2026-33278

Vulnerability from fkie_nvd - Published: 2026-05-20 10:16 - Updated: 2026-07-24 10:10
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.
References
sep@nlnetlabs.nlhttps://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txtMitigation, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:19752
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:23231
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:24369
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/security/cve/CVE-2026-33278
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://bugzilla.redhat.com/show_bug.cgi?id=2479808
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33278.json
Impacted products
Vendor Product Version
nlnetlabs unbound *
To clipboard 

{
  "affected": [
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          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
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  "configurations": [
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      "value": "NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination\u0027s pointer with the source\u0027s pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure."
    },
    {
      "lang": "es",
      "value": "NLnet Labs Unbound 1.19.1 hasta la versi\u00f3n 1.25.0 inclusive tiene una vulnerabilidad en el validador DNSSEC que permite la denegaci\u00f3n de servicio y posible ejecuci\u00f3n remota de c\u00f3digo como resultado de la copia profunda de una estructura de datos y la sobrescritura err\u00f3nea de un puntero de destino. Un adversario puede explotar la vulnerabilidad controlando una zona firmada maliciosa y consultando un Unbound vulnerable. Cuando las subconsultas DS necesitan suspender la validaci\u00f3n debido al agotamiento del presupuesto computacional de NSEC3 (introducido en Unbound 1.19.1), Unbound realiza copias profundas de los mensajes de respuesta para preservarlos durante la desasignaci\u00f3n de la regi\u00f3n de memoria. Un error de asignaci\u00f3n de estructura sobrescribe el puntero del destino con el puntero del origen. Despu\u00e9s de que se libera la regi\u00f3n de la subconsulta, el validador reanudado desreferencia este puntero colgante, lo que provoca un fallo o potencialmente permite la ejecuci\u00f3n de c\u00f3digo arbitrario. Unbound 1.25.1 contiene un parche con una correcci\u00f3n para preservar el puntero correcto al realizar la copia profunda de la estructura de datos."
    }
  ],
  "id": "CVE-2026-33278",
  "lastModified": "2026-07-24T10:10:00.197",
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          "confidentialityImpact": "HIGH",
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          "Recovery": "NOT_DEFINED",
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          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
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          "valueDensity": "NOT_DEFINED",
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          "role": "CISA Coordinator",
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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