CVE-2026-43497 (GCVE-0-2026-43497)

Vulnerability from cvelistv5 – Published: 2026-05-21 12:12 – Updated: 2026-08-05 12:28
VLAI
Title
fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free
Summary
In the Linux kernel, the following vulnerability has been resolved: fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free dlfb_ops_mmap() uses remap_pfn_range() to map vmalloc framebuffer pages to userspace but sets no vm_ops on the VMA. This means the kernel cannot track active mmaps. When dlfb_realloc_framebuffer() replaces the backing buffer via FBIOPUT_VSCREENINFO, existing mmap PTEs are not invalidated. On USB disconnect, dlfb_ops_destroy() calls vfree() on the old pages while userspace PTEs still reference them, resulting in a use-after-free: the process retains read/write access to freed kernel pages. Add vm_operations_struct with open/close callbacks that maintain an atomic mmap_count on struct dlfb_data. In dlfb_realloc_framebuffer(), check mmap_count and return -EBUSY if the buffer is currently mapped, preventing buffer replacement while userspace holds stale PTEs. Tested with PoC using dummy_hcd + raw_gadget USB device emulation.
Severity
7.3 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < 60f711cfd580f86fea8284146ac133804e728f9a (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < 5931f5651ee32bd41b3323256b31fcc8e71336ed (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < e3d9865dacd7435b8465848428210d0f0c673311 (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < 4f312c30f0368e8d2a76aa650dff73f23490b5e7 (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < 18dd358de72d57993422cbb5dfb29ccd74efe192 (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < da9b065cedfd3b574f229d5be594e6aa47a27ae6 (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < a2c53a3822ee26e8d758071815b9ed3bf6669fc1 (git)
Affected: 7433914efd584b22bb49d3e1eee001f5d0525ecd , < 8de779dc40d35d39fa07387b6f921eb11df0f511 (git)
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Linux Linux Affected: 4.19
Unaffected: 0 , < 4.19 (semver)
Unaffected: 5.10.258 , ≤ 5.10.* (semver)
Unaffected: 5.15.209 , ≤ 5.15.* (semver)
Unaffected: 6.1.175 , ≤ 6.1.* (semver)
Unaffected: 6.6.140 , ≤ 6.6.* (semver)
Unaffected: 6.12.88 , ≤ 6.12.* (semver)
Unaffected: 6.18.30 , ≤ 6.18.* (semver)
Unaffected: 7.0.7 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "drivers/video/fbdev/udlfb.c",
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          "vendor": "Linux",
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      "cpeApplicability": [
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free\n\ndlfb_ops_mmap() uses remap_pfn_range() to map vmalloc framebuffer pages\nto userspace but sets no vm_ops on the VMA. This means the kernel cannot\ntrack active mmaps. When dlfb_realloc_framebuffer() replaces the backing\nbuffer via FBIOPUT_VSCREENINFO, existing mmap PTEs are not invalidated.\nOn USB disconnect, dlfb_ops_destroy() calls vfree() on the old pages\nwhile userspace PTEs still reference them, resulting in a use-after-free:\nthe process retains read/write access to freed kernel pages.\n\nAdd vm_operations_struct with open/close callbacks that maintain an\natomic mmap_count on struct dlfb_data. In dlfb_realloc_framebuffer(),\ncheck mmap_count and return -EBUSY if the buffer is currently mapped,\npreventing buffer replacement while userspace holds stale PTEs.\n\nTested with PoC using dummy_hcd + raw_gadget USB device emulation."
        }
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            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "value": "AV:L - The entire exploit is driven by local syscalls (open/mmap/FBIOPUT_VSCREENINFO/close) on the /dev/fbN character device; the attacker is a local software user, not a malicious USB device feeding crafted data, so the vector to the vulnerable component is local rather than physical.\nAC:L - The attacker reliably performs the mmap + realloc-via-ioctl + close sequence and can detect the disconnect before closing; the freed-page mapping is then deterministic with no race or uncontrolled memory-layout condition required to trigger the UAF.\nPR:L - Exploitation requires read/write access to the framebuffer device node, which is available to an ordinary logged-in/video-group user (or kiosk app user) but not to a fully unprivileged unauthenticated actor.\nUI:R - The freeing vfree only runs after a USB disconnect (unregister_framebuffer), so completing the exploit depends on a disconnect event (undock/unplug) performed by the user or environment rather than by the attacker\u0027s own code.\nS:U - The use-after-free corrupts kernel memory within the same security authority (the kernel); there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The process keeps a read mapping to freed pages that are recycled for arbitrary kernel allocations, allowing disclosure of arbitrary kernel memory.\nI:H - The same mapping retains write access to the freed pages once reused by other kernel objects, providing an arbitrary-write primitive suitable for privilege escalation or control-flow hijack.\nA:H - A use-after-free of freed kernel pages readily causes memory corruption and a kernel panic/oops."
            }
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        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:28:19.915Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/60f711cfd580f86fea8284146ac133804e728f9a"
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        {
          "url": "https://git.kernel.org/stable/c/8de779dc40d35d39fa07387b6f921eb11df0f511"
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      "title": "fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43497",
    "datePublished": "2026-05-21T12:12:47.150Z",
    "dateReserved": "2026-05-01T14:12:56.013Z",
    "dateUpdated": "2026-08-05T12:28:19.915Z",
    "state": "PUBLISHED"
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      "date": "2026-10-03",
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      "percentile": "0.05192"
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

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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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.