CVE-2026-97994 vhost/vdpa: reject VRING_NUM larger than device max
A local attacker with access to vhost-vdpa devices can trigger an out-of-bounds read by setting an invalid queue size, potentially causing a kernel crash or information leak.
- 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-2026-97994?
CVE-2026-97994 is a memory corruption vulnerability in Linux, published on 25 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:
vhost/vdpa: reject VRING_NUM larger than device max
vhost_vring_set_num() accepts any non-zero power-of-two queue size that fits in 16 bits. vhost-vdpa then passes that value to set_vq_num() without comparing it with get_vq_num_max().
A process with access to /dev/vhost-vdpa-* can therefore configure a queue larger than the device advertises. With vdpa_sim, the worker can walk descriptors beyond the mapped descriptor ring. KASAN reports a 16-byte out-of-bounds read, corresponding to one vring_desc, in the vringh IOTLB path:
BUG: KASAN: out-of-bounds in _copy_from_iter Read of size 16 copy_from_iotlb copydesc_iotlb vringh_getdesc_iotlb vdpasim_net_work
Cache get_vq_num_max() immediately after reset. Some backends derive it from writable queue-size state, so querying it after SET_NUM may return the current size instead of the device capability. Invalidate the cached value before reset so a failed reset leaves SET_NUM disabled.
For VHOST_SET_VRING_NUM, copy the complete vring state once and use the same index and size for validation, vq->num, and set_vq_num(). This ensures that validation and use operate on the same copied values.
Which versions are affected by CVE-2026-97994?
How do I fix CVE-2026-97994?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-97994 being exploited?
There is no known exploitation of CVE-2026-97994 in the wild and no public exploit code.
Sources
Also known as AZL-104217, BELL-CVE-2026-97994, DEBIAN-CVE-2026-97994, GHSA-h9m6-p5f9-c339, UBUNTU-CVE-2026-97994.