CVE-2026-43203 (GCVE-0-2026-43203)
Vulnerability from cvelistv5
Published
2026-05-06 11:28
Modified
2026-08-05 12:26
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: atm: fore200e: fix use-after-free in tasklets during device removal When the PCA-200E or SBA-200E adapter is being detached, the fore200e is deallocated. However, the tx_tasklet or rx_tasklet may still be running or pending, leading to use-after-free bug when the already freed fore200e is accessed again in fore200e_tx_tasklet() or fore200e_rx_tasklet(). One of the race conditions can occur as follows: CPU 0 (cleanup) | CPU 1 (tasklet) fore200e_pca_remove_one() | fore200e_interrupt() fore200e_shutdown() | tasklet_schedule() kfree(fore200e) | fore200e_tx_tasklet() | fore200e-> // UAF Fix this by ensuring tx_tasklet or rx_tasklet is properly canceled before the fore200e is released. Add tasklet_kill() in fore200e_shutdown() to synchronize with any pending or running tasklets. Moreover, since fore200e_reset() could prevent further interrupts or data transfers, the tasklet_kill() should be placed after fore200e_reset() to prevent the tasklet from being rescheduled in fore200e_interrupt(). Finally, it only needs to do tasklet_kill() when the fore200e state is greater than or equal to FORE200E_STATE_IRQ, since tasklets are uninitialized in earlier states. In a word, the tasklet_kill() should be placed in the FORE200E_STATE_IRQ branch within the switch...case structure. This bug was identified through static analysis.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/atm/fore200e.c"
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      "cpeApplicability": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\natm: fore200e: fix use-after-free in tasklets during device removal\n\nWhen the PCA-200E or SBA-200E adapter is being detached, the fore200e\nis deallocated. However, the tx_tasklet or rx_tasklet may still be running\nor pending, leading to use-after-free bug when the already freed fore200e\nis accessed again in fore200e_tx_tasklet() or fore200e_rx_tasklet().\n\nOne of the race conditions can occur as follows:\n\nCPU 0 (cleanup)           | CPU 1 (tasklet)\nfore200e_pca_remove_one() | fore200e_interrupt()\n  fore200e_shutdown()     |   tasklet_schedule()\n    kfree(fore200e)       | fore200e_tx_tasklet()\n                          |   fore200e-\u003e // UAF\n\nFix this by ensuring tx_tasklet or rx_tasklet is properly canceled before\nthe fore200e is released. Add tasklet_kill() in fore200e_shutdown() to\nsynchronize with any pending or running tasklets. Moreover, since\nfore200e_reset() could prevent further interrupts or data transfers,\nthe tasklet_kill() should be placed after fore200e_reset() to prevent\nthe tasklet from being rescheduled in fore200e_interrupt(). Finally,\nit only needs to do tasklet_kill() when the fore200e state is greater\nthan or equal to FORE200E_STATE_IRQ, since tasklets are uninitialized\nin earlier states. In a word, the tasklet_kill() should be placed in\nthe FORE200E_STATE_IRQ branch within the switch...case structure.\n\nThis bug was identified through static analysis."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - ATM link traffic from a remote peer can cause the adapter IRQ path (`fore200e_interrupt()`) to schedule the vulnerable RX/TX tasklets. The freeing side occurs during adapter removal, but the attacker-controlled stimulus reaches the vulnerable tasklet path over the network-facing ATM device.\nAC:H - The bug requires the non-default `CONFIG_ATM_FORE200E_USE_TASKLET` configuration and a removal event overlapping a pending or running tasklet. The remote attacker can keep interrupts likely, but does not fully control the removal side.\nPR:N - A remote ATM peer does not need credentials or local privileges on the vulnerable host to generate traffic that posts adapter interrupts. Local sysfs unbind/module removal would require real root, but the highest-severity reasonable scenario uses unauthenticated remote traffic coinciding with victim-initiated removal.\nUI:R - Network traffic alone does not free `struct fore200e`; a user/admin action or physical hotplug/removal event must detach, unbind, or remove the adapter. Once removal occurs, pending tasklets can access the freed structure.\nS:U - The corruption occurs within the kernel/driver context and affects resources under the same kernel security authority. There is no VM escape, IOMMU bypass, or cross-scope boundary indicated.\nC:H - This is a use-after-free of the driver\u2019s per-device structure, and the tasklets dereference freed pointers and queues after teardown. Per the kernel scoring guidance, UAF memory corruption is treated as enabling high confidentiality impact.\nI:H - The freed `struct fore200e` can be reallocated or corrupted before tasklet execution, creating a plausible control-flow or arbitrary-write primitive. Per the kernel scoring guidance, UAF memory corruption warrants high integrity impact.\nA:H - The tasklets dereference freed driver state after `kfree(fore200e)`, which can directly cause kernel oops, panic, or hang. Any kernel crash from this UAF is high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:26:31.918Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/91f25749aaf57c47ae1e12478144e6ea8c8562f2"
        },
        {
          "url": "https://git.kernel.org/stable/c/73fbc5d1a9ccb626937500bbd67136f077d8237b"
        },
        {
          "url": "https://git.kernel.org/stable/c/aba0b4bc09376dfc3d53c826514fe38fc8337f52"
        },
        {
          "url": "https://git.kernel.org/stable/c/e075ec9b08f862dade8011481058f7eb5f716c57"
        },
        {
          "url": "https://git.kernel.org/stable/c/97900f512252a59f23d6ce4ab215cc88fed66e68"
        },
        {
          "url": "https://git.kernel.org/stable/c/e4ff4e3ffcf9d5aad380cdd1d8cdc008bb34f97d"
        },
        {
          "url": "https://git.kernel.org/stable/c/5189368f10903956be05062d160b2804bf5e5016"
        },
        {
          "url": "https://git.kernel.org/stable/c/8930878101cd40063888a68af73b1b0f8b6c79bc"
        }
      ],
      "title": "atm: fore200e: fix use-after-free in tasklets during device removal",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43203",
    "datePublished": "2026-05-06T11:28:08.949Z",
    "dateReserved": "2026-05-01T14:12:55.992Z",
    "dateUpdated": "2026-08-05T12:26:31.918Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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