CVE-2026-79979

Что произошло

The arm64 MMU backend invalidates a single virtual address from the TLB with invalidate_tlb_page() in arch/arm64/core/mmu.c, which issued TLBI VAE1{IS} with an operand of virt >> 12. That operand encodes the ASID in bits [63:48], so the invalidation only ever matched ASID 0 (the kernel page tables) and global entries. Memory domains, however, are allocated ASIDs starting at 1 in arch_mem_domain_init(), and every domain-private leaf created by private_map() is mapped with MT_NG, i.e. non-global. A domain's cached translation therefore survived the invalidation. All callers of invalidate_tlb_page() are demand-paging paths. When the eviction algorithm reclaims a frame, page_frame_prepare_locked() in kernel/mmu.c calls arch_mem_page_out(), which marks the kernel leaf invalid, propagates the invalid descriptor into every domain via sync_domains(), and then flushes only ASID 0. do_page_fault() immediately reuses the very same page frame for the incoming mapping through arch_mem_page_in(). A user thread that had already touched the evicted page — a k_mem_partition added with arch_mem_domain_partition_add(), or its own stack mapped by map_thread_stack() — retains a valid EL0 read/write translation to that physical frame under its own ASID. Unprivileged code running in a user thread can drive memory pressure to force eviction and then keep accessing the stale address, obtaining read and write access to whatever the kernel subsequently placed in that frame: supervisor data, another memory domain's partition, or another thread's stack. This defeats the isolation that CONFIG_USERSPACE is meant to enforce, allowing information disclosure and memory corruption up to full compromise of the system. The fix switches the implementation to TLBI VAAE1{IS}, which matches every ASID and both global and non-global entries, so no domain-tagged translation survives a page out, dirty-bit update or access-flag clear. Exploitation requires an arm64 build with both CONFIG_USERSPACE and CONFIG_DEMAND_PAGING enabled, an active backing store, and at least one demand-paged page that is also privately mapped into a user memory domain. The same commit additionally stops globalize_table() from stripping EL0 permission and non-global attributes off domain-private leaves during paging synchronization, which previously caused user threads to lose access to their own partitions and stacks.

Что делать

dpkg-query -W -f='${Package}	${Version}\n'

rpm -qa --qf '%{NAME}\t%{VERSION}-%{RELEASE}\n'

Get-HotFix | Select-Object HotFixID, InstalledOn

Продукты и затронутые версии

{
  "status": "affected",
  "version": "4.3.0",
  "lessThan": "4.5.0",
  "versionType": "semver"
}

CVSS: оценки и векторы

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

Источники и ссылки

{
  "cwes": [
    "cve",
    "nvd"
  ],
  "epss": {
    "source": "epss",
    "received_at": "2026-11-02T21:14:38.624495+00:00"
  },
  "title": {
    "source": "cve",
    "received_at": "2026-11-02T14:08:40.042732+00:00"
  },
  "scores": [
    "cve",
    "nvd"
  ],
  "status": {
    "source": "cve",
    "received_at": "2026-11-02T14:08:40.042732+00:00"
  },
  "affected": [
    "cve"
  ],
  "published": {
    "source": "cve",
    "received_at": "2026-11-02T14:08:40.042732+00:00"
  },
  "solutions": [],
  "percentile": {
    "source": "epss",
    "received_at": "2026-11-02T21:14:38.624495+00:00"
  },
  "references": [
    "cve",
    "nvd"
  ],
  "description": {
    "source": "cve",
    "received_at": "2026-11-02T14:08:40.042732+00:00"
  },
  "workarounds": [],
  "configurations": []
}

Хронология записи

1. Данные обновлены03.11.2026, 00:14
2. Данные обновлены02.11.2026, 00:12
3. Данные обновлены31.10.2026, 11:59
4. Появились сведения об исправлении28.10.2026, 20:22
5. Данные обновлены28.10.2026, 18:06
6. Опубликована28.10.2026, 15:16

Личная заметка и статус

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