MediumCVE-2026-74581

    Linux Kernel: Use-After-Free (CVE-2026-74581)

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

    What is affected, what to do

    A use-after-free vulnerability was found in the Linux kernel's IPv6 FIB rule lookup path. In fib6_rule_suppress(), when a route is suppressed and released via ip6_rt_put_flags(), the res->rt6 pointer is not cleared.

    Update Linux Kernel to version 5.10.265, Linux Kernel to version 5.15.216, Linux Kernel to version 5.5.

    Affected
    • Linux Kernel lt 5.10.84..5.10.265
    • Linux Kernel lt 5.15.7..5.15.216
    • Linux Kernel lt 5.4.164..5.5
    • Linux Kernel lt 5.16..6.1.183
    • Linux Kernel lt 6.2..6.6.151
    • Linux Kernel lt 6.7..6.12.103
    • Linux Kernel lt 6.13..6.18.44
    • Linux Kernel lt 6.19..7.1.8
    Fixed in
    • Linux Kernel 5.10.265
    • Linux Kernel 5.15.216
    • Linux Kernel 5.5
    • Linux Kernel 6.1.183
    • Linux Kernel 6.6.151
    • Linux Kernel 6.12.103
    • Linux Kernel 6.18.44
    • Linux Kernel 7.1.8
    • Linux Kernel 7.2

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

    Metrics

    4.4

    Priority

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

    Source: Vendor (CNA), CVSS v3

    4.4

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 36.5

    Show all metrics
    Severity
    Medium
    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
    56.28 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
    4.4 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
    4.4
    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
    0.4 %
    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
    36.5
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    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
    CISA assessment (SSVC)
    Exploitation: none known · automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 16 October 2026

    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

    A use-after-free vulnerability was found in the Linux kernel's IPv6 FIB rule lookup path. In fib6_rule_suppress(), when a route is suppressed and released via ip6_rt_put_flags(), the res->rt6 pointer is not cleared. If no later rule supplies a replacement route, fib6_rule_lookup() returns the stale (freed) rt6_info to its caller. The subsequent dst_release() then operates on freed memory, hitting rcuref_put_slowpath(). A local attacker who can configure IPv6 routing/FIB rules could trigger this to cause a denial of service (kernel crash) or potentially escalate privileges.

    Source: redhat_csaf, suse_csaf, Debian LTS Advisories, Ubuntu Security Notices, Debian Security Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), Microsoft Security Update Guide

    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
    • 6.19 – < 7.1.8
    • 6.2 – < 6.6.151
    • 5.15.7 – < 5.15.216
    • 5.4.164 – < 5.5
    • 5.16 – < 6.1.183
    • 5.10.84 – < 5.10.265
    • 6.7 – < 6.12.103
    • —
    • 6.13 – < 6.18.44
    • 7.1.8
    • 6.6.151
    • 5.15.216
    • 5.5
    • 6.1.183
    • 5.10.265
    • 6.12.103
    • 7.2
    • 6.18.44
    IBMDataPower Gateway
    • < 11.0.0.3
    • < 10.6.0.11
    • < 10.5.0.23
    • 11.0.0.3
    • 10.6.0.11
    • 10.5.0.23
    IBMQRadar SIEM
    • < 7.6.0.3
    • <7.5.0 UP16 IF01
    • 7.6.0.3
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxtrixie
    Linuxdebianlinux-6.12bookworm
    Linuxubuntulinux-gcp-5.15focal

    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 16 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/354db6243eca59e9d187ffbf8b7955b044ce84dc
      Referenceadded
      —
      https://git.kernel.org/stable/c/5d29b286c9de0b309e94b9ed083aa1a2f429434f
      Referenceadded
      —
      https://git.kernel.org/stable/c/6aea62e433fe1b586202a5fee8b5807ce635e1d7
      Referenceadded
      —
      https://git.kernel.org/stable/c/6d98c70fe0ba8c7708bfd5b2a5174d2086775daa
      Referenceadded
      —
      https://git.kernel.org/stable/c/90c57310e266eb94e4a80d6b15a9ca131d2e82cb
      Referenceadded
      —
      https://git.kernel.org/stable/c/9bad152c42b37499162367fe47867411e62fffa3
      Referenceadded
      —
      https://git.kernel.org/stable/c/a341c091ca0bfae377747b1b59a3bd8ebe18a937
      Referenceadded
      —
      https://git.kernel.org/stable/c/dc3ab04220667f254f4348572b2a0b3febff89fb
      Referenceremoved
      https://git.kernel.org/stable/c/354db6243eca59e9d187ffbf8b7955b044ce84dc
      —
      Referenceremoved
      https://git.kernel.org/stable/c/5d29b286c9de0b309e94b9ed083aa1a2f429434f
      —
      Referenceremoved
      https://git.kernel.org/stable/c/6aea62e433fe1b586202a5fee8b5807ce635e1d7
      —
      Referenceremoved
      https://git.kernel.org/stable/c/6d98c70fe0ba8c7708bfd5b2a5174d2086775daa
      —
      Referenceremoved
      https://git.kernel.org/stable/c/90c57310e266eb94e4a80d6b15a9ca131d2e82cb
      —
      Referenceremoved
      https://git.kernel.org/stable/c/9bad152c42b37499162367fe47867411e62fffa3
      —
      Referenceremoved
      https://git.kernel.org/stable/c/a341c091ca0bfae377747b1b59a3bd8ebe18a937
      —
      Referenceremoved
      https://git.kernel.org/stable/c/dc3ab04220667f254f4348572b2a0b3febff89fb
      —

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

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: yes

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-74581","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:01:10.675016Z"}

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

    3. Record modifiedLinux

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

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

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

    One NVD translation into another language is hidden.

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