Not ratedCVE-2026-99093

    Linux Kernel: NULL Pointer Dereference (CVE-2026-99093)

    Published Last modified Sources: BSI, CVE.org

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: mm: don't schedule deferred kernel page table freeing while booting Booting with a boot-time function tracer and a filter, for example ftrace=function ftrace_filter=pud_free_pmd_page panics on 7.3-rc4 as soon as the tracer starts: [ 23.531178] Starting tracer 'function' [ 23.675800] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN NOPTI [ 23.819917] KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7] [ 23.964025] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.3.0-rc4-fe2ec83746e5-with-fixes-v2+ #195 PREEMPT(undef) [ 24.252248] RIP: 0010:__queue_work+0xab/0xf00 [ 25.981629] Call Trace: [ 26.125727] <TASK> [ 26.413912] ? pagetable_free_kernel+0x20/0x120 [ 26.990283] queue_work_on+0x97/0xf0 [ 27.134382] __cpa_collapse_large_pages+0x501/0x6f0 [ 27.566662] cpa_flush+0x394/0x620 [ 27.998953] change_page_attr_set_clr+0x321/0x4a0 [ 29.151729] set_memory_rox+0xa2/0xf0 [ 29.584018] create_trampoline+0x431/0x6f0 ... [ 44.343347] Kernel panic - not syncing: Attempted to kill the idle task! The boot-time tracer is started from early_trace_init(), which runs before workqueue_init_early().

    Update Linux Kernel to version 6.18.57, Linux Kernel to version 7.2.11.

    Affected
    • Linux Kernel lt 6.18.53..6.18.57
    • Linux Kernel lt 7.2.7..7.2.11
    Fixed in
    • Linux Kernel 6.18.57
    • Linux Kernel 7.2.11

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    Metrics

    —

    Priority

    No value is available for this vulnerability.

    —

    CVSS v3

    No value is available for this vulnerability.

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 5.3

    Show all metrics
    Severity
    Not rated
    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
    30.23 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.

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    no public PoC known
    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
    5.3
    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: mm: don't schedule deferred kernel page table freeing while booting Booting with a boot-time function tracer and a filter, for example ftrace=function ftrace_filter=pud_free_pmd_page panics on 7.3-rc4 as soon as the tracer starts: [ 23.531178] Starting tracer 'function' [ 23.675800] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN NOPTI [ 23.819917] KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7] [ 23.964025] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.3.0-rc4-fe2ec83746e5-with-fixes-v2+ #195 PREEMPT(undef) [ 24.252248] RIP: 0010:__queue_work+0xab/0xf00 [ 25.981629] Call Trace: [ 26.125727] <TASK> [ 26.413912] ? pagetable_free_kernel+0x20/0x120 [ 26.990283] queue_work_on+0x97/0xf0 [ 27.134382] __cpa_collapse_large_pages+0x501/0x6f0 [ 27.566662] cpa_flush+0x394/0x620 [ 27.998953] change_page_attr_set_clr+0x321/0x4a0 [ 29.151729] set_memory_rox+0xa2/0xf0 [ 29.584018] create_trampoline+0x431/0x6f0 ... [ 44.343347] Kernel panic - not syncing: Attempted to kill the idle task! The boot-time tracer is started from early_trace_init(), which runs before workqueue_init_early(). Making its trampoline read-only splits a large page, and CPA collapses it again right away. The split table has been a kernel page table since commit 9e4a3ec3411b ("x86/mm/pat: Allocate split page tables as kernel page tables"), so the collapse frees it through pagetable_free_kernel(), which queues work on system_percpu_wq - still NULL at that point. That commit is correct in itself; it only lets CPA reach pagetable_free_kernel() before the workqueue that function relies on exists. Keep putting the table on the list, but don't schedule the work while the system is still booting. A core_initcall schedules it once to free whatever was queued by then.

    Source: BSI CSAF, BSI WID Portal, 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
    • 6.18.53 – < 6.18.57
    • 7.2.7 – < 7.2.11
    • 6.18.57
    • 7.2.11

    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. ReceivedLinux

      Description added or changed

      Show 5 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: mm: don't schedule deferred kernel page table freeing while booting Booting with a boot-time function tracer and a filter, for example ftrace=function ftrace_filter=pud_free_pmd_page panics on 7.3-rc4 as soon as the tracer starts: [ 23.531178] Starting tracer 'function' [ 23.675800] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN NOPTI [ 23.819917] KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7] [ 23.964025] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.3.0-rc4-fe2ec83746e5-with-fixes-v2+ #195 PREEMPT(undef) [ 24.252248] RIP: 0010:__queue_work+0xab/0xf00 [ 25.981629] Call Trace: [ 26.125727] <TASK> [ 26.413912] ? pagetable_free_kernel+0x20/0x120 [ 26.990283] queue_work_on+0x97/0xf0 [ 27.134382] __cpa_collapse_large_pages+0x501/0x6f0 [ 27.566662] cpa_flush+0x394/0x620 [ 27.998953] change_page_attr_set_clr+0x321/0x4a0 [ 29.151729] set_memory_rox+0xa2/0xf0 [ 29.584018] create_trampoline+0x431/0x6f0 ... [ 44.343347] Kernel panic - not syncing: Attempted to kill the idle task! The boot-time tracer is started from early_trace_init(), which runs before workqueue_init_early(). Making its trampoline read-only splits a large page, and CPA collapses it again right away. The split table has been a kernel page table since commit 9e4a3ec3411b ("x86/mm/pat: Allocate split page tables as kernel page tables"), so the collapse frees it through pagetable_free_kernel(), which queues work on system_percpu_wq - still NULL at that point. That commit is correct in itself; it only lets CPA reach pagetable_free_kernel() before the workqueue that function relies on exists. Keep putting the table on the list, but don't schedule the work while the system is still booting. A core_initcall schedules it once to free whatever was queued by then.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/99xxx/CVE-2026-99093.json">CVE-2026-99093</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/2fb552b0bee70c24c092720028ab4620f5eb2646
      Referenceadded
      —
      https://git.kernel.org/stable/c/7a25ca170c12a9328f6fcf4410713beb516b01c0
      Referenceadded
      —
      https://git.kernel.org/stable/c/df6c704a08bc0925d5db047b0a6221f962bda4d9

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

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