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CVE-2026-74661
mac802154: fix netdev use-after-free in beacon worker
Published 2026-08-22 (2 months ago) by the Linux kernel CNA. Subsystem net/mac802154. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74661 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
mac802154_beacon_worker() reads local->beacon_req under RCU and derives the sub-interface from the request, but then drops the RCU read lock and continues to use both sdata and the embedded wpan_dev. mac802154_stop_beacons_locked() cancels only pending beacon work, clears local->beacon_req and frees the request. A beacon worker that is already running can therefore continue after interface teardown and dereference the freed netdev private area. The scan worker already pins the netdev before leaving RCU. Apply the same lifetime rule to the beacon worker: take a netdev reference while the request is still protected by RCU, and release it on all paths that continue after the reference is acquired.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/mac802154/scan.c
- What this is
- IEEE 802.15.4 SUBSYSTEMMAINTAINERS section matched on net/mac802154/ · linux-wpan@vger.kernel.org · Maintained
- Kernel module
- mac802154
Check it on the machine
grep -w CONFIG_MAC802154 /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w mac802154Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sid, bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- ?
- not established - no Makefile entry for the affected file
- M
- a module where it is built at all; some flavours do not build it
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_MAC802154
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-22 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.12%, higher than 2.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- net/mac802154
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.3 | 6.6.152 | fe820dcc1d8f |
| 6.3 | 6.12.104 | e5fb0e03bc7f |
| 6.3 | 6.18.45 | e6cd416a899e |
| 6.3 | 7.1.9 | 9d067e581597 |
| 6.3 | 7.2 | 5f26a690e8ef |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Exploitation requires local nl802154 generic-netlink syscalls (NL802154_CMD_SEND_BEACONS/STOP_BEACONS) or closing the wpan netdev; the UAF is in beacon workqueue teardown, not in remote 802.15.4 frame parsing, matching netlink-local kernel guidance.
- AC:LAttack complexity, low
- An attacker with CAP_NET_ADMIN controls both sides of the race by starting beaconing then immediately issuing STOP_BEACONS or DEL_INTERFACE while mac802154_transmit_beacon() keeps the worker running; cancel_delayed_work() does not stop in-flight work, making the UAF reliably triggerable.
- PR:LPrivileges required, low
- Starting/stopping beaconing and deleting wpan interfaces require GENL_ADMIN_PERM (netlink_capable CAP_NET_ADMIN); this is reachable from an unprivileged UID via a user namespace (unshare -Urn), not init-namespace root, consistent with mac802154_hwsim and nl802154 gating.
- UI:NUser interaction, none
- No victim interaction is required; the attacker triggers the race entirely through their own netlink and interface lifecycle operations without needing another user to click, pair, or mount anything.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap memory (netdev private ieee802154_sub_if_data) within the same kernel security boundary; it does not cross VM, container, or IOMMU isolation boundaries on its own.
- C:HConfidentiality impact, high
- Use-after-free of the netdev private area (ieee802154_sub_if_data) after interface teardown allows reading freed slab memory; UAF primitives commonly enable arbitrary kernel memory disclosure via heap grooming.
- I:HIntegrity impact, high
- The dangling sdata/wpan_dev pointers enable heap-based memory corruption; UAF of netdev private structures is exploitable for control-flow hijacking and arbitrary kernel write primitives via slab reuse.
- A:HAvailability impact, high
- Concurrent interface teardown while the beacon worker dereferences freed netdev private memory causes kernel oops/panic (KASAN slab-use-after-free), and successful exploitation can crash or hang the system.