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VulnerabilityPublished Updated

CVE-2026-97478: Linux kernel · virt: acrn: Fix irqfd use-after-free during eventfd shutdown

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Authoritative record:CVE-2026-97478· High 7.8

Not known to be exploited · CVSS 7.8 High · fixed in dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48 : patch Linux kernel soon.

Data as of 30 Oct 2026, 16:33 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Linux)CVSS 3.17.8
Patch
Available – fixed in dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48, d8156aacfcabb81f52c20ef89094945434d08079, 666c7f9e07925aa0863348f960e09bb89f8f05a3 +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ aa3b483ff1d71c50b33db154048dff9a8f08ac71, < dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48
Fixed in
  • dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48
LinuxLinuxAffected
  • ≥ aa3b483ff1d71c50b33db154048dff9a8f08ac71, < d8156aacfcabb81f52c20ef89094945434d08079
Fixed in
  • d8156aacfcabb81f52c20ef89094945434d08079
LinuxLinuxAffected
  • ≥ aa3b483ff1d71c50b33db154048dff9a8f08ac71, < 666c7f9e07925aa0863348f960e09bb89f8f05a3
Fixed in
  • 666c7f9e07925aa0863348f960e09bb89f8f05a3
LinuxLinuxAffected
  • ≥ aa3b483ff1d71c50b33db154048dff9a8f08ac71, < 6e9e007ee1dfb54bc2d070550308077ec28dbaec
Fixed in
  • 6e9e007ee1dfb54bc2d070550308077ec28dbaec
LinuxLinuxAffected
  • ≥ aa3b483ff1d71c50b33db154048dff9a8f08ac71, < 0e1152f689847b9db2f05454775d34610c1424c2
Fixed in
  • 0e1152f689847b9db2f05454775d34610c1424c2
LinuxLinuxAffected
  • =5.12
Fixed in–

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(&irqfd->shutdown) 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->vm <-- 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->irqfds 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->lock held and IRQs disabled and therefore cannot take irqfds_lock. - acrn_irqfd_deassign() flushes vm->irqfd_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->irqfds 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.

References

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