# CVE-2026-64570: wifi: mac80211: fix fils_discovery double free on alloc failure

> A double-free vulnerability in the Linux kernel's mac80211 Wi-Fi subsystem can cause a system crash during FILS discovery updates.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-64570, DEBIAN-CVE-2026-64570, GHSA-5gxw-5rpr-7mcv, UBUNTU-CVE-2026-64570

## What is CVE-2026-64570?

CVE-2026-64570 is a high-severity use after free vulnerability in Linux, published on 5 Aug 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: 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().

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2026-64570?


## How do I fix CVE-2026-64570?

Apply the vendor's patch.

## Is CVE-2026-64570 being exploited?

There is no known exploitation of CVE-2026-64570 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64570 and fix it if it is affected.

What it is: CVE-2026-64570 is a high-severity use after free vulnerability in Linux, published on 5 Aug 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-2026-64570 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-2026-64570/ (Markdown: https://insights.sbomify.com/CVE-2026-64570/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64570
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64570
- OSV: https://osv.dev/vulnerability/CVE-2026-64570

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64570/
Summaries are generated and may contain mistakes; the official description above is the record.