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CVE-2026-74510
Bluetooth: mgmt: fix UAF in pair command cancellation
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/bluetooth. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74510 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 | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| 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 | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. 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
The pairing completion and authentication failure callbacks look up the pending MGMT_OP_PAIR_DEVICE command by walking hdev->mgmt_pending. The lookup returned a command that was still linked on the shared pending list, without keeping mgmt_pending_lock held for the later dereference and removal. A concurrent MGMT_OP_CANCEL_PAIR_DEVICE request can remove and free the same pending command before the callback uses it. The reverse race is also possible when cancel_pair_device() gets a command from pending_find() and a callback removes it before the cancel path dereferences it. This can lead to a use-after-free and a second list_del(). Make the pairing lookup helpers transfer ownership of the pending command by removing it from hdev->mgmt_pending while holding mgmt_pending_lock. The callbacks and cancel path then complete the command and free it directly, so racing paths cannot find or free the same command again. Take a temporary hci_conn reference in cancel_pair_device() because the command completion drops the reference stored in the pending command.
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/bluetooth/mgmt.c
- What this is
- BLUETOOTH SUBSYSTEMMAINTAINERS section matched on net/bluetooth/ · linux-bluetooth@vger.kernel.org · Supported
- Kernel module
- bluetooth
Check it on the machine
grep -w CONFIG_BT /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 bluetoothPrints 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.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_BT
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
- 2026-08-15 (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
- 0.14%, higher than 3.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/bluetooth
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.39 | 6.1.184 | 50af4280a587 |
| 2.6.39 | 6.6.151 | 86ed4dd6548c |
| 2.6.39 | 6.12.103 | 7c2a152a897c |
| 2.6.39 | 6.18.44 | c569def320aa |
| 2.6.39 | 7.1.8 | 51be7280980f |
| 2.6.39 | 7.2 | d0a7b48ad092 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | 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
- The UAF is triggered through local AF_BLUETOOTH HCI_CHANNEL_CONTROL management commands (hci_sock_bind/sendmsg -> hci_mgmt_cmd -> pair_device/cancel_pair_device); remote Bluetooth peers cannot issue MGMT_OP_PAIR_DEVICE or MGMT_OP_CANCEL_PAIR_DEVICE over the air.
- AC:LAttack complexity, low
- An attacker controls the race by concurrently issuing MGMT_OP_PAIR_DEVICE and MGMT_OP_CANCEL_PAIR_DEVICE from threads or sockets they own while pairing HCI callbacks fire, and can retry until cancel and completion/auth/SMP paths interleave on the same pending command.
- PR:LPrivileges required, low
- pair_device and cancel_pair_device lack HCI_MGMT_UNTRUSTED and require HCI_SOCK_TRUSTED (CAP_NET_ADMIN at bind); per kernel CNA guidance CAP_NET_ADMIN reachable via unprivileged user namespaces (unshare -Urn) maps to PR:L, consistent with similar Bluetooth mgmt UAF scores.
- UI:NUser interaction, none
- No victim interaction is required beyond a powered Bluetooth controller; the attacker directly sends the conflicting PAIR_DEVICE and CANCEL_PAIR_DEVICE management commands that create the pending entry and race the unlocked find_pairing/pending_find paths against completion callbacks.
- S:UScope, unchanged
- Exploitation corrupts kernel Bluetooth MGMT heap objects (mgmt_pending_cmd) within the same host kernel security authority; this is standard local kernel memory corruption, not a VM, IOMMU, or cross-authority boundary escape.
- C:HConfidentiality impact, high
- Use-after-free of mgmt_pending_cmd when find_pairing or pending_find returns a still-linked command without holding mgmt_pending_lock through later dereference and mgmt_pending_remove, enabling arbitrary kernel memory disclosure via slab reuse of the freed object.
- I:HIntegrity impact, high
- Slab UAF and double list_del on mgmt_pending_cmd during concurrent cancel_pair_device and pairing/auth/SMP completion callbacks provide attacker-influenced heap corruption primitives exploitable for arbitrary kernel writes and control-flow hijacking per kernel UAF guidance.
- A:HAvailability impact, high
- Dereferencing or list_del on a freed mgmt_pending_cmd during the cancel versus callback race causes kernel oops or panic; repeated concurrent PAIR_DEVICE and CANCEL_PAIR_DEVICE commands during active pairing can reliably crash or hang the system.