CVE-2023-52507

What it actually does

Missing bounds check on protocol value before bitmask shift in Linux kernel NFC NCI code allows out-of-bounds shift when an invalid protocol is supplied.

Why it matters to the business

Potential kernel instability or denial of service on NFC-enabled Linux systems; low urgency given minimal exploit activity and no known ransomware use.

How an attack unfolds

An attacker supplies an out-of-range protocol value through the NCI interface; the kernel performs an unchecked shift that may corrupt adjacent memory or trigger a panic, though no public exploits or threat actor campaigns are documented.

How to fix it

Apply the upstream fix in commit 2c231a247a1d1628e41fa1eefd1a5307c41c5f53 or later; rebuild and deploy updated kernel packages; disable NFC kernel modules if NFC is unused.

How to confirm the fix worked

Confirm presence of the added protocol-range assertion in nci.c; verify running kernel contains commit 2c231a247a1d1628e41fa1eefd1a5307c41c5f53 or equivalent backport; test with invalid protocol values under controlled conditions.

Typical attack path

1. Identify or reach a system exposing the NFC NCI subsystem
2. Craft and send an NCI message containing a protocol value >= maximum defined constant
3. Trigger the unchecked bit-shift operation in nci core
4. Observe kernel fault, crash, or undefined behavior

How to detect it

Search kernel logs for NFC-related oops or shift-related warnings; examine audit trails for unexpected NCI protocol negotiation attempts; no widespread exploitation artifacts are known.

What your security team should do

• Prioritize kernel updates on any hosts with CONFIG_NFC_NCI enabled
• Review and disable NFC support where not required
• Monitor for future EPSS increases or KEV inclusion
• Include the fix in standard kernel patch cycles within 30 days