{
  "cveId": "CVE-2026-97478",
  "url": "https://patchblox.com/security/cve/CVE-2026-97478",
  "summary": "CVE-2026-97478 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-97478, released September 24, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "virt: acrn: Fix irqfd use-after-free during eventfd shutdown",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  virt: acrn: Fix irqfd use-after-free during eventfd shutdown  acrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free the same struct hsm_irqfd:    CPU0                                 CPU1   ----                                 ----   eventfd_release()     wake_up_poll(EPOLLHUP)       hsm_irqfd_wakeup()         queue_work(\u0026irqfd-\u003Eshutdown)                                        acrn_irqfd_deassign()                                          hsm_irqfd_shutdown()                                            list_del_init()                                            eventfd_ctx_remove_wait_queue()                                            eventfd_ctx_put()                                          kfree(irqfd)   hsm_irqfd_shutdown_work()     container_of(work, ..., shutdown)     irqfd-\u003Evm                  \u003C-- use-after-free  The deassign path freed the irqfd while a shutdown work item was already queued by EPOLLHUP (or vice versa), so the work item could resurrect a dangling pointer through container_of().  Switch to the lifetime model used by KVM irqfds:   - Deassign/deinit only deactivate the irqfd: remove it from vm-\u003Eirqfds    under irqfds_lock and queue the cleanup work.  - hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the    eventfd waitqueue entry, drops the eventfd reference and frees the    irqfd.  - A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit()    ensures the cleanup work is queued at most once, no matter how many    of {EPOLLHUP, deassign, deinit} fire concurrently.  This is safe to    call from the waitqueue callback, which runs with wqh-\u003Elock held and    IRQs disabled and therefore cannot take irqfds_lock.  - acrn_irqfd_deassign() flushes vm-\u003Eirqfd_wq before returning so the    eventfd is fully detached on return.  acrn_irqfd_deinit() deactivates    every irqfd, flushes the workqueue and only then destroys it, so no    path can queue_work() onto a torn-down workqueue.  - acrn_irqfd_assign() now installs the eventfd waitqueue entry and    publishes the irqfd to vm-\u003Eirqfds under irqfds_lock, so the irqfd is    never visible to deassign/deinit before its waitqueue entry is in    place, and any EPOLLHUP that fires in the assign window queues    cleanup work that blocks on irqfds_lock until publication is done.",
  "published": "2026-09-24T17:17:25Z",
  "severity": "Moderate",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00125,
  "epssPercentile": 0.02257,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97478",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-97478",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-97478",
      "released": "2026-09-24T19:30:44Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-97478",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-97478",
      "released": "2026-09-24T19:30:44Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}