MediumCVE-2026-68169

    Linux Kernel: Use-After-Free (CVE-2026-68169)

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

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    What is affected, what to do

    A flaw was found in the Linux kernel's Multipath TCP (MPTCP) subsystem. A race condition in the `mptcp_pm_userspace_get_local_id` function allows a memory address entry to be freed while still being referenced.

    The available sources name no fixed version. Check the vendor guidance in the references below.

    Conflicting version data — version display is hidden until the data is resolved.

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

    Metrics

    4.7

    Priority

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

    Source: Vendor (CNA), CVSS v3

    4.7

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 11.5

    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
    46.77 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
    4.7 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
    4.7
    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“.

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    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
    11.5
    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

    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 flaw was found in the Linux kernel's Multipath TCP (MPTCP) subsystem. A race condition in the `mptcp_pm_userspace_get_local_id` function allows a memory address entry to be freed while still being referenced. A local attacker could exploit this use-after-free vulnerability, potentially leading to a system crash (denial of service) or arbitrary code execution.

    Source: HKCERT (CC BY 3.0 HK) · HKCERT rating: medium, Ubuntu Security Notices, Debian LTS Advisories, Debian Security Advisories, redhat_csaf, suse_csaf, 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
    • 6.13 – < 6.18.42
    • 6.1.79 – < 6.1.184
    • —
    • 6.8 – < 6.12.103
    • 6.6.18 – < 6.6.151
    • 6.19 – < 7.1.6
    • 6.7.6 – < 6.8
    • 6.18.42
    • 6.1.184
    • 7.2
    • 6.12.103
    • 6.6.151
    • 7.1.6
    • 6.8

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxtrixie
    Linuxubuntulinuxresolute
    Linuxdebianlinux-6.12bookworm
    Linuxubuntulinux-awsresolute
    Linuxubuntulinux-aws-7.0noble
    Linuxubuntulinux-azureresolute
    Linuxubuntulinux-azure-7.0noble
    Linuxubuntulinux-azure-fderesolute
    Linuxubuntulinux-azure-fde-7.0noble
    Linuxubuntulinux-gcpresolute
    Linuxubuntulinux-gcp-7.0noble
    Linuxubuntulinux-gkeresolute
    Linuxubuntulinux-hwe-7.0noble
    Linuxubuntulinux-ibmresolute
    Linuxubuntulinux-oem-7.0resolute
    Linuxubuntulinux-oracleresolute
    Linuxubuntulinux-oracle-7.0noble
    Linuxubuntulinux-realtimeresolute

    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
      Referenceadded
      —
      https://git.kernel.org/stable/c/8ce48d2879aafc0e7a6f8bfc3613c0ba979ec6f5
      Affected versions (publisher)changed
      Linux, Linux
      Linux, Linux

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

    2. Record modifiedLinux

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Linux, Linux
      Linux, Linux

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

    3. ReceivedLinux

      Description added or changed

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Linux, Linux
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: userspace: fix use-after-free in get_local_id In mptcp_pm_userspace_get_local_id(), the address entry is looked up under spinlock, but its id is read after dropping the lock. A concurrent deletion can free the entry between the unlock and the read, leading to UAF. The race window is narrow. It was reproduced only with a locally constructed stress test that repeatedly overlaps an MP_JOIN SYN with a MPTCP_PM_CMD_SUBFLOW_DESTROY request. However, the KASAN report below confirms that the race is reachable: [ 666.319376] BUG: KASAN: slab-use-after-free in mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319386] Read of size 1 at addr ffff888124845610 by task swapper/0/0 ... [ 666.319401] Call Trace: [ 666.319405] <IRQ> [ 666.319408] dump_stack_lvl+0x53/0x70 [ 666.319412] print_address_description.constprop.0+0x2c/0x3b0 [ 666.319418] print_report+0xbe/0x2b0 [ 666.319421] ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319423] kasan_report+0xce/0x100 [ 666.319426] ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319429] mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319433] mptcp_pm_get_local_id+0x371/0x440 ... [ 666.319821] Allocated by task 45539: [ 666.319844] kasan_save_stack+0x33/0x60 [ 666.319855] kasan_save_track+0x14/0x30 [ 666.319858] __kasan_kmalloc+0x8f/0xa0 [ 666.319863] __kmalloc_noprof+0x1e7/0x520 [ 666.319867] sock_kmalloc+0xdf/0x130 [ 666.319885] sock_kmemdup+0x1b/0x40 [ 666.319888] mptcp_userspace_pm_append_new_local_addr+0x261/0x500 [ 666.319910] mptcp_pm_nl_announce_doit+0x16a/0x610 ... [ 666.319967] Freed by task 45560: [ 666.319988] kasan_save_stack+0x33/0x60 [ 666.319991] kasan_save_track+0x14/0x30 [ 666.319994] kasan_save_free_info+0x3b/0x60 [ 666.319998] __kasan_slab_free+0x43/0x70 [ 666.320000] kfree+0x166/0x440 [ 666.320003] sock_kfree_s+0x1d/0x50 [ 666.320007] mptcp_userspace_pm_delete_local_addr.isra.0+0x157/0x200 [ 666.320011] mptcp_pm_nl_subflow_destroy_doit+0x51d/0xea0 Fix by copying the id into a local variable while still holding the lock, and use -1 as a "not found" sentinel.
      Referenceadded
      —
      https://git.kernel.org/stable/c/31ce5af66891f79998fb2e8b8df08e3c98fd72e3
      Referenceadded
      —
      https://git.kernel.org/stable/c/40dde4b5d98279471a70e5c8bb713182738c00d9
      Referenceadded
      —
      https://git.kernel.org/stable/c/9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9
      Referenceadded
      —
      https://git.kernel.org/stable/c/d2c3760b45f2f481a4dd4c5adef4a29dfabd948f
      Referenceadded
      —
      https://git.kernel.org/stable/c/d64f6c02495f3fad674038cfa7ec049671b59e7b

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

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