Description
In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: fix unsol_bcast_probe_resp double free on alloc failure

ieee80211_set_unsol_bcast_probe_resp() calls kfree_rcu() on the old
template before allocating the replacement. If the kzalloc() then fails,
it returns -ENOMEM while link->u.ap.unsol_bcast_probe_resp still points
at the object already queued for freeing. A later update or AP teardown
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 ffff88800d06f300 by task exploit/145
...
__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-128 of size 128

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().
Published: 2026-08-05
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

An attacker that can cause the mac80211 Wi‑Fi subsystem to fail to allocate a new housekeeping object may trigger a double free; the kernel first queues the old object for RCU‑based release and then attempts to free it again if the allocation fails. The resulting double free leads to kernel memory corruption and, potentially, arbitrary code execution. This weakness is a classic example of a double free bug (CWE‑415).

Affected Systems

The flaw resides in the Linux kernel’s mac80211 implementation and affects any Linux kernel that includes the unsol_bcast_probe_resp handling before the fix commit. All kernels that compile the current mac80211 source before the patches identified in the reference commits (0ace76e410d7f…, 1d067abcd37062426c59ec73dbc4e87a63f33fea, ca27a81cd77b698e5eb586a011bee6800c7ee4bd, d62b55b7c7dc62887d7fd5648fb38f0bfaef53ae) are potentially vulnerable. Devices running unpatched Linux kernels with Wi‑Fi support are thus at risk.

Risk and Exploitability

No CVSS or EPSS score is published and the vulnerability is not listed in the CISA KEV catalog. The double free is a severe kernel bug, but there is currently no evidence of a publicly available exploit. The likely attack vector is a local or privileged user who can force an allocation failure or otherwise manipulate the Wi‑Fi driver. Given the lack of known exploitation and the necessity of kernel access, the overall risk is moderate; however, patching remains the recommended course of action.

Generated by OpenCVE AI on August 5, 2026 at 09:26 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade to the latest Linux kernel release that incorporates the mac80211 unsol_bcast_probe_resp double free fix (commits referenced above).
  • If an upgrade is not feasible, disable or remove the wireless driver or suppress the unsol_bcast_probe_resp feature to prevent double free triggers.
  • Enable kernel hardening tools, such as CONFIG_KASAN or other memory corruption detection options, to detect and report potential double free incidents.

Generated by OpenCVE AI on August 5, 2026 at 09:26 UTC.

Tracking

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Advisories

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History

Wed, 05 Aug 2026 09:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-415

Wed, 05 Aug 2026 08:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: fix unsol_bcast_probe_resp double free on alloc failure ieee80211_set_unsol_bcast_probe_resp() calls kfree_rcu() on the old template before allocating the replacement. If the kzalloc() then fails, it returns -ENOMEM while link->u.ap.unsol_bcast_probe_resp still points at the object already queued for freeing. A later update or AP teardown 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 ffff88800d06f300 by task exploit/145 ... __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-128 of size 128 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().
Title wifi: mac80211: fix unsol_bcast_probe_resp double free on alloc failure
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-05T08:08:06.625Z

Reserved: 2026-07-19T15:36:31.797Z

Link: CVE-2026-64568

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-05T10:15:03Z

Weaknesses