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CVE-2026-98290
Bluetooth: RFCOMM: avoid socket lock inversion in listener cleanup
Published 2026-10-06 (13 days 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-2026-98290 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-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6568-1 · 2026-10-16 · text | 6.12.113-1 | Update the kernel and reboot. DSA-6568-1 shipped the fix on 2026-10-16, in 6.12.113-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.8-1 | Update the kernel and reboot. Fixed in 7.2.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.8-1 | Update the kernel and reboot. Fixed in 7.2.8-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
rfcomm_sock_cleanup_listen() closes unaccepted child sockets through rfcomm_sock_close(), which takes the child socket lock before rfcomm_dlc_close() acquires rfcomm_mutex. The RFCOMM worker takes these locks in reverse order while handling connections and DLC state changes, so lockdep reports a possible deadlock. Close dequeued children without taking their socket lock. The accept queue owns a reference to each child, and bt_accept_dequeue() locks the child while unlinking it and clearing its parent pointer. Dropping the child lock makes it important to prevent a concurrent rfcomm_connect_ind() from enqueueing a new child after cleanup observes an empty queue. Set a listening socket to BT_CLOSED while its lock is still held, before dropping the lock and draining the queue. The state check in rfcomm_connect_ind() then rejects new children once cleanup starts.
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/rfcomm/sock.c
- What this is
- BLUETOOTH SUBSYSTEMMAINTAINERS section matched on net/bluetooth/ · linux-bluetooth@vger.kernel.org · Supported
- Kernel module
- rfcomm
Check it on the machine
grep -wE 'CONFIG_BT|CONFIG_BT_RFCOMM' /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 rfcommPrints 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
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_BT, CONFIG_BT_RFCOMM
- Reads as
- all on means the file is compiled; any one off means it is not.
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
- 2026-10-06 (13 days ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.26%, higher than 16.2% 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 |
|---|---|---|
| 5.15 | 5.15.222 | eb4adaa46e4c |
| 5.15 | 6.1.189 | 4aafb47301a7 |
| 5.15 | 6.6.158 | c741977e413f |
| 5.15 | 6.12.112 | c6792c441767 |
| 5.15 | 6.18.54 | bfce253f039e |
| 5.15 | 7.2.8 | 18174b166547 |
| 5.15 | 7.3 | 801fb950cae7 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DSA-6568-1 | 2026-10-16 | trixie 6.12.113-1 | 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
- A Bluetooth peer drives both halves of this bug. Its RFCOMM SABM creates a child in rfcomm_connect_ind(), and its later DISC makes krfcommd call rfcomm_sk_state_change() on that child (taking lock_sock(child) under rfcomm_mutex, and dereferencing bt_sk(child)->parent). Bluetooth requires radio range, so the vector is Adjacent.
- AC:HAttack complexity, high
- The peer can send SABM and DISC at will, but both the ABBA deadlock and the late-enqueue window need the victim to close its listener at that moment. That window runs from rfcomm_sock_shutdown dropping the listener lock to cleanup_listen setting BT_CLOSED, and the peer cannot control when the application closes the socket.
- PR:NPrivileges required, none
- rfcomm_connect_ind() only checks for a BT_LISTEN socket on the channel and for room in the backlog before it enqueues a child, so the peer needs no credentials.
- UI:NUser interaction, none
- No victim action beyond normal operation is needed. A service closing its RFCOMM listener on its own (exit, restart, or Bluetooth teardown) is a timing condition and is counted in AC:H.
- S:UScope, unchanged
- The deadlock and the dangling parent pointer both stay inside kernel RFCOMM socket state and do not cross a virtualization or hardware boundary.
- C:HConfidentiality impact, high
- A child enqueued after the drain keeps bt_sk(sk)->parent pointing at the listener, but bt_accept_enqueue takes no reference on it, so rfcomm_sock_kill frees the listener while the pointer is still live. A later state change then reads the freed sock through parent->sk_data_ready, a use-after-free that can be groomed for disclosure.
- I:HIntegrity impact, high
- On the peer's DISC, rfcomm_sk_state_change calls bt_accept_unlink(), which does list_del on the freed listener's accept_q and decrements its backlog, then makes an indirect call through the freed parent->sk_data_ready. That is a write to freed memory and a call through a function pointer an attacker can replace.
- A:HAvailability impact, high
- The ABBA blocks krfcommd forever while it holds rfcomm_mutex (rfcomm_dlc_close in the closer against lock_sock(child) in rfcomm_sk_state_change). That stops all RFCOMM processing and hangs the closing task, and the use-after-free path can oops the kernel.