# CVE-2025-71132: smc91x: fix broken irq-context in PREEMPT_RT

> A race condition in the smc91x network driver under PREEMPT_RT can cause kernel warnings and potential instability, requiring a patch to fix IRQ context handling.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2025-71132, DEBIAN-CVE-2025-71132, GHSA-52xq-4j7g-g3fj, ROOT-OS-DEBIAN-12-CVE-2025-71132, ROOT-OS-DEBIAN-13-CVE-2025-71132, ROOT-OS-UBUNTU-2204-CVE-2025-71132, ROOT-OS-UBUNTU-2404-CVE-2025-71132, UBUNTU-CVE-2025-71132

## What is CVE-2025-71132?

CVE-2025-71132 is a high-severity vulnerability in Linux kernel, published on 14 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

smc91x: fix broken irq-context in PREEMPT_RT

When smc91x.c is built with PREEMPT_RT, the following splat occurs
in FVP_RevC:

[   13.055000] smc91x LNRO0003:00 eth0: link up, 10Mbps, half-duplex, lpa 0x0000
[   13.062137] BUG: workqueue leaked atomic, lock or RCU: kworker/2:1[106]
[   13.062137]      preempt=0x00000000 lock=0->0 RCU=0->1 workfn=mld_ifc_work
[   13.062266] C
** replaying previous printk message **
[   13.062266] CPU: 2 UID: 0 PID: 106 Comm: kworker/2:1 Not tainted 6.18.0-dirty #179 PREEMPT_{RT,(full)}
[   13.062353] Hardware name:  , BIOS
[   13.062382] Workqueue: mld mld_ifc_work
[   13.062469] Call trace:
[   13.062494]  show_stack+0x24/0x40 (C)
[   13.062602]  __dump_stack+0x28/0x48
[   13.062710]  dump_stack_lvl+0x7c/0xb0
[   13.062818]  dump_stack+0x18/0x34
[   13.062926]  process_scheduled_works+0x294/0x450
[   13.063043]  worker_thread+0x260/0x3d8
[   13.063124]  kthread+0x1c4/0x228
[   13.063235]  ret_from_fork+0x10/0x20

This happens because smc_special_trylock() disables IRQs even on PREEMPT_RT,
but smc_special_unlock() does not restore IRQs on PREEMPT_RT.
The reason is that smc_special_unlock() calls spin_unlock_irqrestore(),
and rcu_read_unlock_bh() in __dev_queue_xmit() cannot invoke
rcu_read_unlock() through __local_bh_enable_ip() when current->softirq_disable_cnt becomes zero.

To address this issue, replace smc_special_trylock() with spin_trylock_irqsave().

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2025-71132?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-71132?

Apply the vendor's patch.

## Is CVE-2025-71132 being exploited?

There is no known exploitation of CVE-2025-71132 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71132 and fix it if it is affected.

What it is: CVE-2025-71132 is a high-severity vulnerability in Linux kernel, published on 14 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-71132 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-71132/ (Markdown: https://insights.sbomify.com/CVE-2025-71132/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71132
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71132
- OSV: https://osv.dev/vulnerability/CVE-2025-71132

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71132/
Summaries are generated and may contain mistakes; the official description above is the record.