# CVE-2026-74325: wifi: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link

> A use-after-free vulnerability in the Linux kernel mt76 WiFi driver allows attackers to cause denial of service or execute code via improper memory handling.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-74325, DEBIAN-CVE-2026-74325, GHSA-4hx5-9m7x-6xgv, UBUNTU-CVE-2026-74325

## What is CVE-2026-74325?

CVE-2026-74325 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

wifi: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link

mt76_put_vif_phy_link() frees the offchannel mlink with plain kfree()
after rcu_assign_pointer(NULL). However, rcu_assign_pointer only prevents
future RCU readers from obtaining the pointer -- it does not wait for
existing readers that already hold it via rcu_dereference.

The TX datapath (e.g. mt7996_mac_write_txwi) dereferences mlink->wcid
and mlink->idx under rcu_read_lock. If a TX softirq obtained the pointer
via rcu_dereference just before the NULL assignment, it will dereference
freed memory after the kfree.

struct mt76_vif_link already contains an rcu_head field that is unused at
this free site -- a developer oversight, since the adjacent
kfree_rcu_mightsleep call for rx_sc in the same function shows the
pattern was understood.

Replace kfree(mlink) with kfree_rcu(mlink, rcu_head).

## Which versions are affected by CVE-2026-74325?


## How do I fix CVE-2026-74325?

Apply the vendor's patch.

## Is CVE-2026-74325 being exploited?

There is no known exploitation of CVE-2026-74325 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74325 and fix it if it is affected.

What it is: CVE-2026-74325 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74325 in the wild and no public exploit code.

Affected product: Linux. 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-2026-74325/ (Markdown: https://insights.sbomify.com/CVE-2026-74325/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74325
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74325
- OSV: https://osv.dev/vulnerability/CVE-2026-74325

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74325/
Summaries are generated and may contain mistakes; the official description above is the record.