HighCVE-2026-66785

    Red Hat Advanced Cluster Management for Kubernetes 2.16: Insufficient Verification of Data Authenticity (CVE-2026-66785)

    Published Last modified Sources: Red Hat, CVE.org

    What is affected, what to do

    A flaw was found in Submariner. This vulnerability allows a malicious cluster (spoke) to redirect network traffic from other connected clusters (peer clusters) by publishing a specially crafted network endpoint.

    Update Red Hat Advanced Cluster Management for Kubernetes 2.16 to version 1790670439, Red Hat Advanced Cluster Management for Kubernetes 2.16 to version 1790670231, Red Hat Advanced Cluster Management for Kubernetes 2.16 to version 1790670243.

    Affected
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670439
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670231
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670243
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670508
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670233
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670912
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 lt *..1790670254
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788023916
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788023940
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788105072
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788043964
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788043961
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788073481
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 lt *..1788043970
    Fixed in
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670439
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670231
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670243
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670508
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670233
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670912
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670254
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788023916
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788023940
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788105072
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788043964
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788043961
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788073481
    • Red Hat Advanced Cluster Management for Kubernetes 2.17 1788043970

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    Metrics

    8.7

    Priority

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

    Source: NVD, CVSS v3

    8.7

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: Red Hat, CVE.org

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 10.5

    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
    68.41 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
    8.7 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
    8.7
    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
    0.2 %
    Low — model estimates < 1% 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
    10.5
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    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-345

    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 Submariner. This vulnerability allows a malicious cluster (spoke) to redirect network traffic from other connected clusters (peer clusters) by publishing a specially crafted network endpoint. The system fails to properly validate the network subnets provided by the malicious cluster, enabling it to declare arbitrary network ranges. Consequently, all network traffic intended for these arbitrary ranges from peer clusters will be rerouted through the attacker's tunnel, potentially leading to unauthorized information disclosure or network disruption.

    Source: redhat_csaf, cvelistv5, NVD (NIST)

    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
    Red HatRed Hat Advanced Cluster Management for Kubernetes 2
    • —
    • —
    Red HatRed Hat Advanced Cluster Management for Kubernetes 2.16
    • < 1790670233
    • < 1790670243
    • < 1790670231
    • < 1790670254
    • < 1790670508
    • < 1790670439
    • < 1790670912
    • 1790670233
    • 1790670243
    • 1790670231
    • 1790670254
    • 1790670508
    • 1790670439
    • 1790670912
    Red HatRed Hat Advanced Cluster Management for Kubernetes 2.17
    • < 1788023916
    • < 1788043961
    • < 1788105072
    • < 1788023940
    • < 1788073481
    • < 1788043970
    • < 1788043964
    • 1788023916
    • 1788043961
    • 1788105072
    • 1788023940
    • 1788073481
    • 1788043970
    • 1788043964

    Vendors and products

    Weakness classes (CWE)

    • CWE-345Insufficient Verification of Data Authenticity

      Class

      The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

      Entry at MITRE CWE-345

    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

      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/2026/66xxx/CVE-2026-66785.json">CVE-2026-66785</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:85227

      Source identifier: secalert@redhat.com

    2. Record modifiedRed Hat

      CVSS V3.1: AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

      CVSS V3.1: before AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N, after —

      Weakness type: CWE-345

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
      CVSSremoved
      AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
      —
      Weakness type (CWE)added
      —
      CWE-345
      Weakness type (CWE)removed
      CWE-732
      —

      Source identifier: secalert@redhat.com

    3. Record modifiedRed Hat

      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/2026/66xxx/CVE-2026-66785.json">CVE-2026-66785</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:63016

      Source identifier: secalert@redhat.com

    4. Record modifiedRed Hat

      CVSS V3.1: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

      Source identifier: secalert@redhat.com

    5. Record modifiedRed Hat

      CVSS V3.1: before AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H, after —

      Weakness type: CWE-732

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSremoved
      AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
      —
      Weakness type (CWE)added
      —
      CWE-732
      Weakness type (CWE)removed
      CWE-20
      —
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2026-66785
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2507530
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2026-66785
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2507530
      —

      Source identifier: secalert@redhat.com

    Show one older change

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-66785","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-25T15:16:29.726764Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    One NVD translation into another language is hidden.

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