CVE-2024-23963 Overview
CVE-2024-23963 is a stack-based buffer overflow in the Alpine Halo9 in-vehicle infotainment platform, specifically the ILX-F509 model. The flaw resides in the PBAP_DecodeVCARD function, which handles vCard entries received through the Bluetooth Phone Book Access Profile (PBAP). The function fails to validate the length of user-supplied data before copying it into a fixed-size stack buffer. A network-adjacent attacker who successfully pairs a malicious Bluetooth device with the head unit can trigger the overflow and execute arbitrary code as root. The vulnerability is tracked under [CWE-94] (Improper Control of Generation of Code).
Critical Impact
Successful exploitation yields arbitrary code execution as root on the infotainment unit, giving attackers full control over the affected vehicle head unit.
Affected Products
- Alps Alpine ILX-F509 Halo9 in-vehicle infotainment head unit
- Alps Alpine ILX-F509 firmware (all versions prior to the vendor fix)
- Deployments integrating the affected Halo9 Bluetooth stack
Discovery Timeline
- 2025-01-31 - CVE-2024-23963 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-23963
Vulnerability Analysis
The flaw lies in the Phone Book Access Profile (PBAP) implementation used by the Halo9 Bluetooth stack. When a paired device transmits a vCard object, the PBAP_DecodeVCARD routine parses the incoming record and copies fields into a stack-allocated buffer. The function does not enforce a maximum length on those fields before invoking the copy operation.
An attacker who supplies an oversized vCard property overwrites the return address and adjacent stack data. Because the infotainment process runs with root privileges, arbitrary code execution grants unrestricted access to the underlying Linux-based platform. From that foothold, an attacker can pivot to connected vehicle buses, exfiltrate paired-device data, or persist across reboots by modifying firmware components.
Exploitation requires user interaction to accept the Bluetooth pairing request, which is why the CVSS user interaction metric is marked required. Once paired, no further user action is needed.
Root Cause
The root cause is missing bounds checking on attacker-controlled input inside PBAP_DecodeVCARD. The function trusts the length of vCard fields received over Bluetooth and copies them into a fixed stack buffer without validating that the source length is smaller than the destination. This pattern maps to [CWE-94] as reported by the coordinating advisory.
Attack Vector
The attack vector is Adjacent Network. The attacker must be within Bluetooth range of the target vehicle and must successfully pair a controlled device with the head unit. After pairing, the attacker sends a crafted PBAP vCard entry containing an oversized field. The malformed record triggers the overflow during parsing and redirects execution into attacker-controlled memory.
No verified public proof-of-concept code has been released. Refer to the Zero Day Initiative Advisory ZDI-24-850 for the coordinated disclosure details.
Detection Methods for CVE-2024-23963
Indicators of Compromise
- Unexpected Bluetooth pairing events on the ILX-F509 head unit from unknown devices
- Head unit crashes, spontaneous reboots, or service restarts following PBAP synchronization
- Anomalous outbound network activity from the infotainment unit after Bluetooth pairing
- vCard transfers containing fields significantly larger than typical contact record sizes
Detection Strategies
- Monitor Bluetooth pairing logs on Alpine Halo9 units and flag pairings from unrecognized MAC addresses
- Inspect PBAP traffic captures for vCard properties exceeding realistic field lengths (for example, FN, TEL, or EMAIL fields over several hundred bytes)
- Correlate infotainment crash telemetry with recent Bluetooth pairing or PBAP synchronization events
Monitoring Recommendations
- Enable and retain Bluetooth pairing audit logs where the vehicle platform supports it
- Track firmware version reporting from fleet vehicles to confirm patched builds are deployed
- Establish a baseline of normal PBAP transfer sizes to identify statistical outliers
How to Mitigate CVE-2024-23963
Immediate Actions Required
- Apply the firmware update issued by Alps Alpine for the ILX-F509 head unit as soon as it is available through authorized service channels
- Remove untrusted or unrecognized paired Bluetooth devices from the head unit
- Disable Bluetooth pairing mode when not actively pairing a known device
Patch Information
Alps Alpine addresses the flaw in updated ILX-F509 firmware distributed through authorized dealers and service centers. Refer to the Zero Day Initiative Advisory ZDI-24-850 for coordinated disclosure references. No vendor advisory URL was published in the NVD record at the time of writing; contact Alps Alpine support to confirm the fixed firmware version for your unit.
Workarounds
- Restrict Bluetooth pairing to trusted personal devices and remove stale pairings from the head unit
- Keep the head unit out of discoverable mode except during controlled pairing sessions
- Avoid accepting pairing prompts from unknown devices, especially in public parking environments
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
