# CVE-2026-74366: wifi: ath12k: fix NULL deref in change_sta_links for unready link

> A NULL pointer dereference in the ath12k WiFi driver allows local attackers to crash the system via specific link state transitions.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74366, DEBIAN-CVE-2026-74366, GHSA-j4ff-3xfg-cv3g, UBUNTU-CVE-2026-74366

## What is CVE-2026-74366?

CVE-2026-74366 is a 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: ath12k: fix NULL deref in change_sta_links for unready link

_ieee80211_set_active_links() calls _ieee80211_link_use_channel() for
each newly-added link and WARN_ON_ONCE()s if it fails. The call uses
assign_on_failure=true, which allows mac80211 to continue despite
driver failures, but when a mac80211-level channel validation fails
(e.g., combinations check, DFS, or no available radio),
drv_assign_vif_chanctx() is never reached. Since ath12k_mac_vdev_create()
is only called from that path, arvif->is_created remains false and
arvif->ar remains NULL for the failed link.

The subsequent drv_change_sta_links() call reaches
ath12k_mac_op_change_sta_links(), which allocates an arsta and sets
ahsta->links_map |= BIT(link_id) for the broken link before checking
whether the link is ready. When the vdev was never created, only
station_add() is skipped, but the link remains in links_map.

Any subsequent operation iterating links_map and dereferencing arvif->ar
without a NULL check will crash. Two observed examples are NULL deref in
ath12k_mac_ml_station_remove() on disconnect and in ath12k_mac_op_set_key()
when wpa_supplicant installs PTK keys.

  BUG: Unable to handle kernel NULL pointer dereference at 0x00000000
  pc : ath12k_mac_station_post_remove+0x40/0xe8 [ath12k]
  Call trace:
   ath12k_mac_station_post_remove+0x40/0xe8 [ath12k]
   ath12k_mac_op_sta_state+0xb60/0x1720 [ath12k]
   drv_sta_state+0x100/0xbd8 [mac80211]
   __sta_info_destroy_part2+0x148/0x178 [mac80211]
   ieee80211_set_disassoc+0x500/0x678 [mac80211]

  BUG: Unable to handle kernel NULL pointer dereference at 0x00000000
  pc : ath12k_mac_op_set_key+0x1f8/0x2c0 [ath12k]
  Call trace:
   ath12k_mac_op_set_key+0x1f8/0x2c0 [ath12k]
   drv_set_key+0x70/0x100 [mac80211]
   ieee80211_key_enable_hw_accel+0x78/0x260 [mac80211]
   ieee80211_add_key+0x16c/0x2ac [mac80211]
   nl80211_new_key+0x138/0x280 [cfg80211]

Fix this by checking arvif->is_created before calling
ath12k_mac_alloc_assign_link_sta(). This prevents the broken link from
entering links_map, so all subsequent operations iterating the bitmap
are protected. The reliability of arvif->is_created across all error
paths is ensured by the preceding patch.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3

## Which versions are affected by CVE-2026-74366?


## How do I fix CVE-2026-74366?

Apply the vendor's patch.

## Is CVE-2026-74366 being exploited?

There is no known exploitation of CVE-2026-74366 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74366 and fix it if it is affected.

What it is: CVE-2026-74366 is a 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-2026-74366 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-2026-74366/ (Markdown: https://insights.sbomify.com/CVE-2026-74366/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74366
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74366
- OSV: https://osv.dev/vulnerability/CVE-2026-74366

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74366/
Summaries are generated and may contain mistakes; the official description above is the record.