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CVE-2026-89500 (GCVE-0-2026-89500)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-13 06:30
VLAI
Title
ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page
Summary
In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page Discarding a cached reader page after a concurrent ring buffer resize uses the new global subbuf_order for the free_pages() call. This mismatched order may crashes the kernel or leaks memory because the cached page was allocated under the old size. Save the actual free_page order alongside the page address to ensure we always refer to the correct value and do not rely on the potentially stalled cpu_buffer->subbuf_order value. The simplest is to make free_page a buffer_data_read_page which already covers exactly what we need: a page address and a page order.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 8e7b58c27b3c567316a51079b375b846f9223bba , < a1dabe68fb53730bc0be60c5dbfd3f4c560084e7 (git)
Affected: 8e7b58c27b3c567316a51079b375b846f9223bba , < d787d509bdf6c88c85e095247daf7456cb7fb772 (git)
Affected: 8e7b58c27b3c567316a51079b375b846f9223bba , < 7a1fb95de5404134f8758c1295ce88986bdf117c (git)
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Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.18.51 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/ring_buffer.c"
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              "versionType": "original_commit_for_fix"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Make cpu_buffer::free_page a buffer_data_read_page\n\nDiscarding a cached reader page after a concurrent ring buffer resize\nuses the new global subbuf_order for the free_pages() call. This\nmismatched order may crashes the kernel or leaks memory because the cached\npage was allocated under the old size.\n\nSave the actual free_page order alongside the page address to ensure we\nalways refer to the correct value and do not rely on the potentially\nstalled cpu_buffer-\u003esubbuf_order value. The simplest is to make\nfree_page a buffer_data_read_page which already covers exactly what we\nneed: a page address and a page order."
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
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              "lang": "en",
              "value": "AV:L - The bug is reached only via local tracefs: write() to buffer_subbuf_size_kb (buffer_subbuf_size_write -\u003e ring_buffer_subbuf_order_set) racing read/splice/close of per_cpu/cpuN/trace_pipe_raw (ring_buffer_alloc_read_page / ring_buffer_free_read_page) or instance rmdir (rb_free_cpu_buffer). No network, adjacent-radio, or physical path exists.\nAC:L - The attacker owns both sides of the race: one thread toggles buffer_subbuf_size_kb while another caches or discards a reader page via trace_pipe_raw. The window includes synchronize_rcu() and GFP_KERNEL allocation of every new sub-buffer, so the mismatch is reliably retryable with no condition outside attacker control.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC, with no capable() check. buffer_subbuf_size_kb is 0640 and trace_pipe_raw is 0440; Android/Perfetto, ChromeOS, and distro tracing groups routinely delegate these to unprivileged accounts, matching CVE-2024-50207, CVE-2025-38101, and CVE-2026-74634.\nUI:N - Exploitation uses the attacker\u0027s own file descriptors and threads (write buffer_subbuf_size_kb, read/close trace_pipe_raw, optional instance rmdir). No separate victim mount, click, or configuration action is required.\nS:U - Wrong-order free_pages() and reuse of a cached reader page corrupt kernel ring-buffer and buddy-allocator pages within the same OS security authority. This enables local privilege escalation but does not cross VM, IOMMU, container, or hardware trust boundaries.\nC:H - cpu_buffer-\u003efree_page stored no allocation order, so a cached page allocated under the old subbuf size can be discarded or reused with the new order. Over-free and undersized-page swap are page UAF/OOB reads; recycled buddy pages and ring-buffer contents can be disclosed through subsequent trace_pipe_raw reads.\nI:H - free_pages() with a larger-than-allocated order returns neighboring in-use pages to the buddy allocator (page UAF/write). ring_buffer_read_page() can also swap that undersized cached page into the live writer path, producing out-of-bounds kernel stores exploitable for control-flow hijack.\nA:H - Mismatched-order free_pages() corrupts the buddy allocator and the commit states this may crash the kernel; UAF/OOB on ring-buffer pages also oops/panic. The attacker chooses the order delta via buffer_subbuf_size_kb and can retrigger the race at will."
            }
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        "dateUpdated": "2026-09-13T06:30:07.394Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/7a1fb95de5404134f8758c1295ce88986bdf117c"
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    "cveId": "CVE-2026-89500",
    "datePublished": "2026-09-11T19:43:49.392Z",
    "dateReserved": "2026-09-11T19:38:34.715Z",
    "dateUpdated": "2026-09-13T06:30:07.394Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Make cpu_buffer::free_page a buffer_data_read_page\n\nDiscarding a cached reader page after a concurrent ring buffer resize\nuses the new global subbuf_order for the free_pages() call. This\nmismatched order may crashes the kernel or leaks memory because the cached\npage was allocated under the old size.\n\nSave the actual free_page order alongside the page address to ensure we\nalways refer to the correct value and do not rely on the potentially\nstalled cpu_buffer-\u003esubbuf_order value. The simplest is to make\nfree_page a buffer_data_read_page which already covers exactly what we\nneed: a page address and a page order."
          }
        ],
        "id": "CVE-2026-89500",
        "lastModified": "2026-09-13T07:17:13.210",
        "metrics": {
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      "cve": "CVE-2026-89500",
      "id": "CVE-2026-89500",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "200",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89500.json",
      "version": "3"
    },
    "suse_vex": {
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      "current_release_date": "2026-09-15T00:58:48Z",
      "cve": "CVE-2026-89500",
      "id": "CVE-2026-89500",
      "initial_release_date": "2026-09-12T16:27:26Z",
      "product_status:known_affected": "17",
      "product_status:known_not_affected": "336",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89500",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89500.json",
      "version": "5"
    }
  }
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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