CVE-2023-40283

What it actually does

Use-after-free in l2cap_sock_release due to mishandled child sockets in the Linux kernel Bluetooth L2CAP implementation, enabling memory corruption with local access.

Why it matters to the business

Local attackers could execute arbitrary code with kernel privileges or cause system crashes on affected Linux devices using Bluetooth, leading to data compromise or denial of service; low exploitation likelihood but high impact on confidentiality, integrity, and availability.

How an attack unfolds

An attacker with local access on a vulnerable Linux system manipulates Bluetooth L2CAP sockets to trigger improper child socket handling during release, resulting in a use-after-free that can be leveraged for memory corruption and privilege escalation.

How to fix it

Update the Linux kernel to a version containing commit 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 or later (equivalent to 6.4.10 or newer stable releases); rebuild and deploy custom kernels if using GIT sources.

How to confirm the fix worked

Verify the running kernel version is at least 6.4.10 or contains the referenced commit; test Bluetooth socket operations under load to confirm absence of use-after-free crashes or memory errors.

Typical attack path

1. Obtain local access to a Linux system with Bluetooth enabled
2. Create and manipulate L2CAP sockets to establish parent-child relationships
3. Trigger socket release under specific timing conditions to cause use-after-free
4. Exploit the freed memory for arbitrary read/write or code execution

How to detect it

Inspect kernel logs for Bluetooth L2CAP related crashes or warnings around socket release; look for unusual process activity involving Bluetooth after local access events; no widespread exploitation indicators reported.

What your security team should do

• Prioritize kernel upgrades on all Bluetooth-enabled Linux systems within standard patching cycles
• Monitor upstream kernel releases and distribution security advisories for backports
• Restrict local user access where feasible until patched
• Review Bluetooth usage policies to limit exposure on high-value systems