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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-80934 being exploited?
There is no known exploitation of CVE-2026-80934 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80934, DEBIAN-CVE-2026-80934, GHSA-8jh2-32h2-grwf, UBUNTU-CVE-2026-80934.