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CVE-2026-64406
Bluetooth: fix UAF in bt_accept_dequeue()
Published 2026-07-25 (3 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-2026-64406 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-4720-1 · 2026-08-05 · text | 6.1.180-1 | Update the kernel and reboot. DLA-4720-1 shipped the fix on 2026-08-05, in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.96-1 | Update the kernel and reboot. Fixed in 6.12.96-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
bt_accept_get() takes a temporary reference before dropping the accept queue lock. bt_accept_dequeue() currently drops that reference before bt_accept_unlink(), leaving only the queue reference. bt_accept_unlink() drops the queue reference. The subsequent sock_hold() therefore accesses freed memory if it was the final reference, as observed by KASAN during listening L2CAP socket cleanup. Retain the temporary queue-walk reference through unlink and hand it to the caller on success. Drop it explicitly on the closed and not-yet-connected paths.
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/af_bluetooth.c
net/bluetooth/l2cap_sock.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
- 2026-07-25 (3 months ago)source
- CVSS
- 8.0 high
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.27%, higher than 18.5% 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 |
|---|---|---|
| 5.10.259 | 5.10.261 | c0577c55219b |
| 5.15.210 | 5.15.212 | 96ad400d5132 |
| 6.1.175 | 6.1.178 | 0a98ff4e7b86 |
| 6.6.142 | 6.6.145 | c66a95e60b65 |
| 6.12.92 | 6.12.96 | 6303ed4bbe00 |
| 6.18.34 | 6.18.39 | 26168db1ce5a |
| 7.1 | 7.1.4 | 50c662bdcd51 |
| 7.1 | 7.2 | 4bd0b274054f |
| 7.0.11 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | tracker |
| DLA-4723-1 | 2026-08-07 | bullseye 6.1.180-1~deb11u1 | tracker |
| DLA-4720-1 | 2026-08-05 | bookworm 6.1.180-1 | tracker |
| DLA-4717-1 | 2026-08-05 | bullseye 5.10.262-1 | 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:AAttack vector, adjacent network
- The vulnerable child is created through an incoming Bluetooth link, with its teardown driven by connection and disconnection events from a nearby peer. Bluetooth radio reachability is adjacent rather than routable network access.
- AC:LAttack complexity, low
- The attacker can control listener cleanup and use an adjacent peer to connect and disconnect before the fixed channel becomes ready, producing the final queue-only reference state. The trigger is repeatable and Bluetooth BR/EDR support is a common default configuration.
- PR:LPrivileges required, low
- Unprivileged SOCK_STREAM or SOCK_SEQPACKET L2CAP sockets and dynamic or fixed-CID binds require no capability; only raw sockets and reserved PSM binds are privileged. Although AF_BLUETOOTH requires init_net, an ordinary host user or user namespace without a new network namespace can reach it.
- UI:NUser interaction, none
- The attacker can close their own listener while controlling the peer connection lifecycle, requiring no action from another user.
- S:UScope, unchanged
- Exploitation compromises the vulnerable host kernel but does not inherently cross a VM, IOMMU, or other security-authority boundary.
- C:HConfidentiality impact, high
- The freed struct sock comes from the general kmalloc-2k cache and can be reclaimed with attacker-controlled data. Subsequent socket and channel dereferences can be developed into arbitrary kernel-memory disclosure.
- I:HIntegrity impact, high
- The UAF causes an atomic write to freed memory followed by further operations on the freed socket and channel, enabling heap-spray-based corruption and potential control-flow hijacking.
- A:HAvailability impact, high
- The confirmed post-free write can cause a kernel oops or panic, and the attacker can repeat the connection, disconnection, and cleanup sequence.