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CVE-2026-53071
Bluetooth: l2cap: Add missing chan lock in l2cap_ecred_reconf_rsp
Published 2026-06-24 (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-2026-53071 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-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| 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 | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
l2cap_ecred_reconf_rsp() calls l2cap_chan_del() without holding l2cap_chan_lock(). Every other l2cap_chan_del() caller in the file acquires the lock first. A remote BLE device can send a crafted L2CAP ECRED reconfiguration response to corrupt the channel list while another thread is iterating it. Add l2cap_chan_hold() and l2cap_chan_lock() before l2cap_chan_del(), and l2cap_chan_unlock() and l2cap_chan_put() after, matching the pattern used in l2cap_ecred_conn_rsp() and l2cap_conn_del().
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_core.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
- 2026-06-24 (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
- 0.43%, higher than 35.7% 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 |
|---|---|---|
| 5.7 | 5.10.258 | 96dca51715d8 |
| 5.7 | 5.15.209 | 330b20ec9791 |
| 5.7 | 6.1.175 | 0ccd75c51f62 |
| 5.7 | 6.6.141 | 77a853aec710 |
| 5.7 | 6.12.91 | fe1188abdae9 |
| 5.7 | 6.18.33 | dc89961b76f1 |
| 5.7 | 7.0.10 | 5501d055a1ce |
| 5.7 | 7.1 | 42776497cdbc |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | 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
- Bluetooth L2CAP LE signaling is reachable over a nearby Bluetooth Low Energy link from a remote BLE peer. This requires adjacent radio proximity rather than IP network access.
- AC:LAttack complexity, low
- The vulnerable path is triggered by a crafted ECRED reconfiguration response after an ECRED channel/reconfiguration exists, and ECRED is enabled by default. The race is between attacker-timed peer signaling and normal channel/socket activity, with no rare external condition required.
- PR:NPrivileges required, none
- The receive path performs no OS privilege or capability check on the remote peer before dispatching the L2CAP_ECRED_RECONF_RSP. A nearby BLE device can send the crafted response as protocol input without local credentials.
- UI:NUser interaction, none
- In a plausible phone, embedded, or IoT deployment, an ECRED-using service can maintain/reconfigure BLE channels without a victim performing an exploit-time action. The attacker only needs to send the malicious BLE response at the protocol level.
- S:UScope, unchanged
- The corruption occurs inside the kernel Bluetooth/L2CAP subsystem and impacts the same kernel security authority. It is not a VM escape or other cross-scope boundary bypass.
- C:HConfidentiality impact, high
- The missing channel lock permits unsynchronized channel deletion and list/lifetime corruption in kernel memory. As memory corruption, it is defensible to treat it as capable of yielding kernel information disclosure primitives.
- I:HIntegrity impact, high
- Concurrent `l2cap_chan_del()` without the required channel lock can corrupt kernel list/object state and potentially be shaped beyond a simple disconnect. Under the required conservative scoring rule, this kernel memory corruption supports high integrity impact.
- A:HAvailability impact, high
- At minimum, corrupted L2CAP channel list/lifetime state can cause kernel oops, panic, or hang. The vulnerable code can be reached repeatedly by a malicious nearby BLE peer.