LowCVE-2026-99223

    Linux Kernel: security vulnerability (CVE-2026-99223)

    Published Last modified Sources: BSI, Msrc Update Guide, CVE.org

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: keys: make keyring indexes independent of kernel addresses KEYCTL_READ returns the serial numbers in a keyring in associative-array traversal order. The first word of the index is a public, deterministic hash of the type pointer, domain pointer and description.

    Update Linux Kernel to version 5.10.273, Linux Kernel to version 5.15.224, Linux Kernel to version 6.1.191.

    Affected
    • Linux Kernel lt 3.13..5.10.273
    • Linux Kernel lt 5.11..5.15.224
    • Linux Kernel lt 5.16..6.1.191
    • Linux Kernel lt 6.2..6.6.161
    • Linux Kernel lt 6.7..6.12.115
    • Linux Kernel lt 6.13..6.18.60
    • Linux Kernel lt 6.19..7.2.14
    • Linux Kernel lt 7.3..7.3.1
    • Linux Kernel lt 7.4..7.4-rc1
    Fixed in
    • Linux Kernel 5.10.273
    • Linux Kernel 5.15.224
    • Linux Kernel 6.1.191
    • Linux Kernel 6.6.161
    • Linux Kernel 6.12.115
    • Linux Kernel 6.18.60
    • Linux Kernel 7.2.14
    • Linux Kernel 7.3.1
    • Linux Kernel 7.4-rc1

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

    Metrics

    3.3

    Priority

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

    Source: Vendor (CNA), CVSS v3

    3.3

    CVSS v3

    Severity Low on the scale from 0 to 10.

    Source: BSI, Msrc Update Guide, CVE.org

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 7.9

    Show all metrics
    Severity
    Low
    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
    47.00 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
    3.3 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
    3.3
    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
    7.9
    Low — this CVE sits in the lower 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

    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
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    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

    In the Linux kernel, the following vulnerability has been resolved: keys: make keyring indexes independent of kernel addresses KEYCTL_READ returns the serial numbers in a keyring in associative-array traversal order. The first word of the index is a public, deterministic hash of the type pointer, domain pointer and description. An unprivileged user can therefore insert keys with known descriptions, predict their order for each possible KASLR slide, and recover the kernel image address. On an x86-64 build with 16 MiB alignment, 45 user keys suffice to distinguish the candidate slides. Remove the addresses from the whole index, not just its first hash word. Assign each key type and domain a nonzero 64-bit ID and hash those IDs and the description with a once-initialized SipHash key. Use the full IDs in the later index chunks as well. Truncating or hashing the IDs there would lose the guarantee that distinct type/domain/description tuples have a differing index bit. Allocate IDs lazily since private key types need not be registered. Cache them in the index key so tree walks and copies of an existing index do not need to dereference a type descriptor that may have been unregistered. Keep the 32-bit chunk layout and diff_objects() bit offsets consistent, and retain the separate root slot for keyrings used by recursive search. The key comparison, permissions and userspace data format are unchanged; only the address-dependent in-memory ordering is replaced.

    Source: BSI WID Portal, BSI CSAF, Microsoft Security Update Guide, 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
    LinuxLinux
    • 7.3 – < 7.3.1
    • 6.7 – < 6.12.115
    • 5.11 – < 5.15.224
    • 5.16 – < 6.1.191
    • 6.13 – < 6.18.60
    • 6.2 – < 6.6.161
    • 6.19 – < 7.2.14
    • 3.13 – < 5.10.273
    • 7.4 – < 7.4-rc1
    • 7.3.1
    • 6.12.115
    • 5.15.224
    • 6.1.191
    • 6.18.60
    • 6.6.161
    • 7.2.14
    • 5.10.273
    • 7.4-rc1

    Vendors and products

    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 modifiedLinux

      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/2026/99xxx/CVE-2026-99223.json">CVE-2026-99223</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/de891c73c1cf41ac8de12c07fa2c84d6a912ad0c

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    2. ReceivedLinux

      Description added or changed

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: keys: make keyring indexes independent of kernel addresses KEYCTL_READ returns the serial numbers in a keyring in associative-array traversal order. The first word of the index is a public, deterministic hash of the type pointer, domain pointer and description. An unprivileged user can therefore insert keys with known descriptions, predict their order for each possible KASLR slide, and recover the kernel image address. On an x86-64 build with 16 MiB alignment, 45 user keys suffice to distinguish the candidate slides. Remove the addresses from the whole index, not just its first hash word. Assign each key type and domain a nonzero 64-bit ID and hash those IDs and the description with a once-initialized SipHash key. Use the full IDs in the later index chunks as well. Truncating or hashing the IDs there would lose the guarantee that distinct type/domain/description tuples have a differing index bit. Allocate IDs lazily since private key types need not be registered. Cache them in the index key so tree walks and copies of an existing index do not need to dereference a type descriptor that may have been unregistered. Keep the 32-bit chunk layout and diff_objects() bit offsets consistent, and retain the separate root slot for keyrings used by recursive search. The key comparison, permissions and userspace data format are unchanged; only the address-dependent in-memory ordering is replaced.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/99xxx/CVE-2026-99223.json">CVE-2026-99223</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/13fc051269d670810d9e314061b61c6dd06116a0
      Referenceadded
      —
      https://git.kernel.org/stable/c/61ac0585d9f4344d3dfb84b5edff1fee7d532897
      Referenceadded
      —
      https://git.kernel.org/stable/c/8451d4a4c43127c3b9fdf9fc9ff3fea5539a61f9
      Referenceadded
      —
      https://git.kernel.org/stable/c/84f7c699f8d139f743c7dc11ef41d085690955bb
      Referenceadded
      —
      https://git.kernel.org/stable/c/9ebe824d55983c9f063a2c9ef1a08b29812d406f
      Referenceadded
      —
      https://git.kernel.org/stable/c/9f084ef0beb68091e96ab96f0e95579aac8a77f9
      Referenceadded
      —
      https://git.kernel.org/stable/c/a113eba06bd1183c614d7994864d6e7054140cb9
      Referenceadded
      —
      https://git.kernel.org/stable/c/e108b22999edbc6f431466baf6b2016c19b7ed31

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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