CVE-2026-80896 mshv: Fix race in mshv_irqfd_deassign
A race condition in the Linux kernel's mshv driver allows local attackers to trigger a double free or use-after-free, potentially leading to privilege escalation or system crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80896?
CVE-2026-80896 is a vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mshv: Fix race in mshv_irqfd_deassign
mshv_irqfd_deactivate() and the hlist traversal of pt_irqfds_list require pt->pt_irqfds_lock to be held, but mshv_irqfd_deassign() omits it. This races with the EPOLLHUP path in mshv_irqfd_wakeup(), which does take the lock before calling mshv_irqfd_deactivate().
Additionally, mshv_irqfd_deactivate() uses hlist_del() which poisons the node pointers rather than resetting them. Since mshv_irqfd_is_active() relies on hlist_unhashed() (checks pprev == NULL), a poisoned node still appears active. If a concurrent path calls mshv_irqfd_deactivate() again on the same irqfd, the guard fails to prevent a double hlist_del() on poisoned pointers.
Fix both issues: - Add the missing spin_lock_irq/spin_unlock_irq around the list traversal in mshv_irqfd_deassign(), matching mshv_irqfd_release(). - Use hlist_del_init() instead of hlist_del() so the node is properly marked as unhashed after removal, making the is_active guard reliable.
Which versions are affected by CVE-2026-80896?
How do I fix CVE-2026-80896?
Apply the vendor's patch.
Is CVE-2026-80896 being exploited?
There is no known exploitation of CVE-2026-80896 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80896, DEBIAN-CVE-2026-80896, GHSA-322j-r4fq-pwx8, UBUNTU-CVE-2026-80896.