CVE-2026-90127 virtio: rtc: time out alarm requests
A missing timeout in Linux kernel virtio RTC alarm requests can cause a system hang during device removal, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90127?
CVE-2026-90127 is a denial of service vulnerability in Linux, published on 17 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:
virtio: rtc: time out alarm requests
RTC class operations run with rtc_device.ops_lock held. The virtio RTC alarm requests currently wait without a timeout for the device to return their requestq buffers.
On surprise removal, virtio-pci marks the virtqueues broken before unregistering the virtio device. If an alarm request is waiting when the device stops responding, viortc_remove() blocks in viortc_class_stop() while trying to acquire ops_lock. The request cannot complete and device removal hangs until the waiting task is signalled.
Use the same 60-second timeout as clock read requests for alarm reads, alarm programming, and alarm interrupt enable requests. The existing message reference counting keeps a timed-out request alive until a late response or device teardown.
Which versions are affected by CVE-2026-90127?
How do I fix CVE-2026-90127?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-90127 being exploited?
There is no known exploitation of CVE-2026-90127 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-90127, DEBIAN-CVE-2026-90127, GHSA-h4vf-f6xj-7ccf, UBUNTU-CVE-2026-90127.