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CVE-2026-97994

Linux: vhost/vdpa: reject VRING_NUM larger than device max

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.20%Chance of exploitation activity in the next 30 days, higher than 9% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in4875c65ca53797a0a402fe2bb54d1b12f28b3cdaAlso 1d09201d81b7d3e276860cc7b7dbf6c6cbe8e9b4, 68232102f20fc961327fb9e0f605a7eaadf030a9 and 1 moreCVE List
Published25 Sep 2026Updated 19 Oct 2026CVE List

What fixes it

  • 4875c65ca53797a0a402fe2bb54d1b12f28b3cdaLinuxCVE List
  • 1d09201d81b7d3e276860cc7b7dbf6c6cbe8e9b4LinuxCVE List
  • 68232102f20fc961327fb9e0f605a7eaadf030a9LinuxCVE List
  • 59522639a7d71cff4e20d594d0b9ea30dd0c77e0LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 12

  • Linuxaffected: 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 4875c65ca53797a0a402fe2bb54d1b12f28b3cdaCVE List
  • Linuxaffected: 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 1d09201d81b7d3e276860cc7b7dbf6c6cbe8e9b4CVE List
  • Linuxaffected: 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 68232102f20fc961327fb9e0f605a7eaadf030a9CVE List
  • Linuxaffected: 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 59522639a7d71cff4e20d594d0b9ea30dd0c77e0CVE List
  • Linuxaffected: 4c8cf31885f69e86be0b5b9e6677a26797365e1d before ccb1dc7c527f8c925925cf92afc76ae590dac311CVE List
  • Linuxaffected: 5.7CVE List
  • Linuxunaffected: all versions before 5.7CVE List
  • Linuxunaffected: 6.6.158 through 6.6.*CVE List
  • Linuxunaffected: 6.12.111 through 6.12.*CVE List
  • Linuxunaffected: 6.18.53 through 6.18.*CVE List
  • Linuxunaffected: 7.2.7 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5