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CVE-2026-53358
Bluetooth: L2CAP: use chan timer to close channels in cleanup_listen()
Published 2026-07-02 (4 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-2026-53358 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
l2cap_chan_close() removes the channel from conn->chan_l, which must be done under conn->lock. cleanup_listen() runs under the parent sk_lock, so acquiring conn->lock would invert the established conn->lock -> chan->lock -> sk_lock order. Instead of calling l2cap_chan_close() directly, schedule l2cap_chan_timeout with delay 0 to close the channel asynchronously. The timeout handler already acquires conn->lock and chan->lock in the correct order. The timer is only armed when chan->conn is still set: if it is already NULL, l2cap_conn_del() has already processed this channel (l2cap_chan_del + l2cap_sock_teardown_cb + l2cap_sock_close_cb), so there is nothing left to do. If l2cap_conn_del() races in after the timer is armed, __clear_chan_timer() inside l2cap_chan_del() cancels it; if the timer has already fired, the handler returns harmlessly because chan->conn was cleared.
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/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
- 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
- 2026-07-02 (4 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.23%, higher than 12.8% 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 |
|---|---|---|
| 3.4 | 5.10.259 | 3634cbdc2eb4 |
| 3.4 | 5.15.210 | e1c100e2d61b |
| 3.4 | 6.1.176 | deb8493a8fa5 |
| 3.4 | 6.6.143 | 89dec9204171 |
| 3.4 | 6.12.93 | 50dfec218808 |
| 3.4 | 6.18.35 | 859d3ace791e |
| 3.4 | 7.0.12 | 7555fd885a06 |
| 3.4 | 7.1 | 8c8e620467a7 |
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 L2CAP child channels are created and torn down through Bluetooth BR/EDR or LE signaling from a nearby peer, so the remote reachability is adjacent. Bluetooth is not generally Internet-routable, but phones, embedded devices, and kiosks commonly expose this surface to nearby attackers.
- AC:LAttack complexity, low
- The bug is a race, but the attacker can repeatedly create queued L2CAP children and trigger disconnect/cleanup timing; related reports show the listen/close versus HCI-disconnect race reproducing reliably. Under the required rule, the attacker-controlled repeatable race is scored Low complexity.
- PR:NPrivileges required, none
- A nearby Bluetooth peer can reach L2CAP connection setup before application authentication, including low-security/SDP-style services, without an OS account on the target. If a local service lifecycle participates in cleanup, that is target state rather than attacker privilege.
- UI:NUser interaction, none
- No victim user action such as opening a file or accepting a prompt is required once Bluetooth and a listening L2CAP service are present. The attacker can drive the Bluetooth connection and disconnect attempts directly.
- S:UScope, unchanged
- The corruption occurs inside the Linux kernel Bluetooth stack and impacts the same kernel security authority. There is no VM escape, IOMMU bypass, or cross-authority boundary change indicated.
- C:HConfidentiality impact, high
- The old path called l2cap_chan_close() without conn->lock, allowing unlocked removal from conn->chan_l and races with l2cap_conn_del() over sock/l2cap_chan lifetime. This is kernel memory corruption/UAF-adjacent behavior, which is defensibly exploitable for high confidentiality impact.
- I:HIntegrity impact, high
- The race can corrupt kernel list/refcount state around l2cap_chan and sock teardown, giving a plausible route to use-after-free style heap manipulation. Kernel memory corruption is scored as high integrity impact under the provided guidance.
- A:HAvailability impact, high
- At minimum, racing channel cleanup and connection deletion can cause list corruption, double teardown, UAF, KASAN splats, oops, or panic. A repeatable kernel crash is high availability impact.