# CVE-2026-80825: wifi: mt76: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb

> A missing headroom check in the mt7925 WiFi driver causes a kernel panic when bridging wired traffic to a USB WiFi AP, leading to denial of service.

- **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:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-80825, GHSA-82xc-6pqj-mvc4, UBUNTU-CVE-2026-80825

## What is CVE-2026-80825?

CVE-2026-80825 is a vulnerability in Linux, published on 4 Sep 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: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb

mt7925_usb_sdio_tx_prepare_skb() pushes a TX descriptor and a USB
header onto every skb and assumes the headroom for them is already
there. That holds for locally generated traffic, where mac80211
reserves hw->extra_tx_headroom, but forwarded frames are sent through
ieee80211_8023_xmit(), which does not reserve it. Bridge a wired
interface to an mt7925u AP and the first forwarded frame that arrives
short panics the kernel:

 skbuff: skb_under_panic: len:415 put:4 tail:0x19b end:0x640 dev:wlan1
 kernel BUG at net/core/skbuff.c:212!
 Call trace:
  skb_panic+0x58/0x60 (P)
  skb_push+0x58/0x60
  mt7925_usb_sdio_tx_prepare_skb+0xf8/0x1b8 [mt7925_common]
  mt76u_tx_queue_skb+0xa0/0x1f8 [mt76_usb]
  __mt76_tx_queue_skb+0x54/0xe8 [mt76]
  mt76_txq_schedule.part.0+0x204/0x478 [mt76]
  mt76_txq_schedule_all+0x50/0x80 [mt76]
  mt792x_tx_worker+0x68/0x100 [mt792x_lib]
  __mt76_worker_fn+0x84/0x150 [mt76]

Whether a given setup hits it depends on how much headroom the ingress
netdev leaves in its rx skbs. Reproduced on a Raspberry Pi 5 bridging
onboard ethernet to a Netgear A9000; originally reported on an MT7986
router running OpenWrt. Nick Morrow's testing on a Pi 4 (bcmgenet),
which leaves more headroom, helped narrow the trigger to the ingress
path.

The same bug was fixed on mt7921 by commit 98c4d0abf5c4 ("mt76:
mt7921: don't assume adequate headroom for SDIO headers"), but mt7925
was copied from mt7921 without the fix. Add the same guard here.

## Which versions are affected by CVE-2026-80825?


## How do I fix CVE-2026-80825?

Apply the vendor's patch.

## Is CVE-2026-80825 being exploited?

There is no known exploitation of CVE-2026-80825 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80825 and fix it if it is affected.

What it is: CVE-2026-80825 is a vulnerability in Linux, published on 4 Sep 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-2026-80825 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-2026-80825/ (Markdown: https://insights.sbomify.com/CVE-2026-80825/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80825
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80825
- OSV: https://osv.dev/vulnerability/CVE-2026-80825

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80825/
Summaries are generated and may contain mistakes; the official description above is the record.