HighCVE-2026-5946

    Invalid handling of CLASS != IN (CVE-2026-5946)

    Published Last modified Sources: Red Hat, SUSE, Debian LTS, Msrc Update Guide, CVE.org, Ubuntu, EUVD, Debian, BSI

    What is affected, what to do

    A flaw was found in the bind component, specifically within the `named` daemon. This vulnerability allows a remote attacker to send specially crafted Domain Name System (DNS) messages.

    Update bind to version 9.21.22, BIND to version 9.20.23.

    Affected
    • ISC BIND 9 lte 9.11.0..9.16.50
    • ISC BIND 9 lte 9.18.0..9.18.48
    • ISC BIND 9 lte 9.20.0..9.20.22
    • ISC BIND 9 lte 9.21.0..9.21.21
    • ISC BIND 9 lte 9.11.3-S1..9.16.50-S1
    • ISC BIND 9 lte 9.18.11-S1..9.18.48-S1
    • ISC BIND 9 lte 9.20.9-S1..9.20.22-S1

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: Red Hat, SUSE, Debian LTS, Msrc Update Guide, CVE.org, Ubuntu, EUVD, Debian, BSI

    1.9 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 80.0

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    106.47 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.5 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.5
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    1.9 %
    Moderate — model estimates 1-10% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    80.0
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-20, CWE-125, CWE-617, CWE-754, CWE-843

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A flaw was found in the bind component, specifically within the `named` daemon. This vulnerability allows a remote attacker to send specially crafted Domain Name System (DNS) messages. These messages, which use unusual classes or meta-classes, can trigger assertion failures in the `named` daemon when processed. Successful exploitation leads to an application level Denial of Service (DoS), making the DNS service unavailable.

    Source: redhat_csaf, suse_csaf, Debian LTS Advisories, Microsoft Security Update Guide, cvelistv5, NVD (NIST), Ubuntu Security Notices, ENISA EUVD, CVE.org (MITRE), Debian Security Advisories, BSI WID Portal, BSI CSAF

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    ISCBIND 9
    • 9.18.0 – ≤ 9.18.48
    • 9.18.11-S1 – ≤ 9.18.48-S1
    • 9.20.9-S1 – ≤ 9.20.22-S1
    • 9.11.3-S1 – ≤ 9.16.50-S1
    • 9.20.0 – ≤ 9.20.22
    • 9.21.0 – ≤ 9.21.21
    • 9.11.0 – ≤ 9.16.50
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    iscbind
    • 9.11.0 – ≤ 9.16.50
    • 9.21.0 – < 9.21.22
    • 9.20.0 – < 9.20.23
    • 9.18.0 – < 9.18.49
    • —
    • 9.21.22
    • 9.20.23
    • 9.18.49
    Internet Systems ConsortiumBIND
    • < 9.20.23
    • < 9.18.49
    • < 9.21.22
    • 9.20.23
    • 9.18.49
    • 9.21.22

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianbind9bookworm
    Linuxdebianbind9bullseye
    Linuxdebianbind9trixie

    Weakness classes (CWE)

    • CWE-20Improper Input Validation

      Class

      The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

      Entry at MITRE CWE-20

    • CWE-125Out-of-bounds Read

      Base

      The product reads data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-125

    • CWE-617Reachable Assertion

      Base

      The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

      Entry at MITRE CWE-617

    • CWE-754Improper Check for Unusual or Exceptional Conditions

      Class

      The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

      Entry at MITRE CWE-754

    • CWE-843Access of Resource Using Incompatible Type ('Type Confusion')

      Base

      The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

      Entry at MITRE CWE-843

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedRed Hat ADP

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:65851

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    2. Record modifiedRed Hat ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/5xxx/CVE-2026-5946.json">CVE-2026-5946</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:62549

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    3. Record modifiedRed Hat ADP

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/5xxx/CVE-2026-5946.json">CVE-2026-5946</a>

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    4. Record modifiedisc.org

      Show 12 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://downloads.isc.org/isc/bind9/9.18.49
      Referenceadded
      —
      https://downloads.isc.org/isc/bind9/9.20.23
      Referenceadded
      —
      https://downloads.isc.org/isc/bind9/9.21.22
      Referenceadded
      —
      https://kb.isc.org/docs/cve-2026-5946
      Referenceremoved
      https://downloads.isc.org/isc/bind9/9.18.49
      —
      Referenceremoved
      https://downloads.isc.org/isc/bind9/9.20.23
      —
      Referenceremoved
      https://downloads.isc.org/isc/bind9/9.21.22
      —
      Referenceremoved
      https://kb.isc.org/docs/cve-2026-5946
      —
      Reference typeremoved
      https://downloads.isc.org/isc/bind9/9.18.49 Types: Patch
      —
      Reference typeremoved
      https://downloads.isc.org/isc/bind9/9.20.23 Types: Patch
      —
      Reference typeremoved
      https://downloads.isc.org/isc/bind9/9.21.22 Types: Patch
      —
      Reference typeremoved
      https://kb.isc.org/docs/cve-2026-5946 Types: Vendor Advisory
      —

      Source identifier: security-officer@isc.org

    5. Record modifiedRed Hat ADP

      Show 23 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:20334
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:23360
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:24338
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:24339
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:24367
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:24368
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:55441
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:57189
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:60383
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2026-5946
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2479771
      Referenceadded
      —
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5946.json
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:20334
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:23360
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:24338
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:24339
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:24367
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:24368
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:55441
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:57189
      —
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2026-5946
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2479771
      —
      Referenceremoved
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5946.json
      —

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    Show 2 older changes

    1. Record modifiedRed Hat ADP

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+8)
      Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+9)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    2. Record modifiedRed Hat ADP

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:57189

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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