# CVE-2026-80934: wifi: mt76: mt7996: fix TX DMA mapping leak for AddBA req frames

> A memory leak in the mt7996 WiFi driver causes resource exhaustion and denial of service when WED is enabled and clients reconnect frequently.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80934, DEBIAN-CVE-2026-80934, GHSA-8jh2-32h2-grwf, UBUNTU-CVE-2026-80934

## What is CVE-2026-80934?

CVE-2026-80934 is a denial of service vulnerability in Linux, published on 11 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: mt7996: fix TX DMA mapping leak for AddBA req frames

mt7996/mt7992 hand the firmware a HW MAC-TXP for AddBA req action frames
(MT_TXD7_MAC_TXD, set in mt7996_mac_write_txwi_80211()), but are otherwise
FW-TXP devices. On tx free mt76_connac_txp_skb_unmap() therefore decodes
the per-frame txp as a struct mt76_connac_fw_txp. For a MAC-TXP the
fw_txp.nbuf byte aliases the AddBA TID word (MT_TXP1_TID_ADDBA), which is
always zero, so the unmap loop runs zero times and the skb DMA mapping in
buf[1] is never unmapped. buf[1].skip_unmap is set unconditionally, so the
generic DMA-ring cleanup skips it as well.

Each AddBA req therefore leaks one TX DMA mapping, roughly one per
(re)association. With WED enabled these mappings are bounced through the
WED swiotlb pool, so under continuous client reconnect churn the pool is
exhausted after ~1-2 days, after which DMA mapping fails for WED, the WiFi
MCU and other on-SoC consumers.

Keep the deferred (token release) unmap that the design relies on, and add
an mt7996-specific txp unmap that inspects MT_TXD7_MAC_TXD and unmaps
buf[1] from the MAC-TXP layout for those frames, delegating to
mt76_connac_txp_skb_unmap() otherwise.

## Which versions are affected by CVE-2026-80934?


## How do I fix CVE-2026-80934?

Apply the vendor's patch.

## Is CVE-2026-80934 being exploited?

There is no known exploitation of CVE-2026-80934 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80934 and fix it if it is affected.

What it is: CVE-2026-80934 is a denial of service vulnerability in Linux, published on 11 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-2026-80934 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-2026-80934/ (Markdown: https://insights.sbomify.com/CVE-2026-80934/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80934
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80934
- OSV: https://osv.dev/vulnerability/CVE-2026-80934

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80934/
Summaries are generated and may contain mistakes; the official description above is the record.