A newly disclosed vulnerability in the Android Bluetooth stack which is being tracked as CVE-2025–48539 has security teams on high alert. The flaw, rated 8.0 on the CVSS scale, stems from a use-after-free condition in acl_arbiter.cc, specifically within the SendPacketToPeer function. A threat actor with adjacent network access can exploit the bug to trigger out-of-bounds reads and potentially execute arbitrary code without user interaction.

The vulnerability affects a wide range of Android devices running unpatched kernels, and has already been observed in targeted attacks against enterprise mobile fleets. Google’s September 2025 security bulletin confirms active exploitation in the wild.

Security researchers warn that the flaw bypasses traditional Bluetooth hardening techniques and may be chained with other privilege escalation vectors to gain full device control. The attack surface is particularly concerning for BYOD environments and mobile-first workforces.

Analyst Comment

“CVE-2025–48539 is a textbook example of how race conditions in low-level protocol handlers can become remote execution vectors. The fact that it’s zero-click and adjacent-access makes it ideal for stealthy lateral movement in mobile-heavy environments. Organisations should treat this as a high-priority patch and consider Bluetooth segmentation policies.”

Red Team Perspective

Kill Chain Mapping

Diamond Model

Blue Team Perspective

Defensive Controls

• Kernel patching via September 2025 Android update
• Enable CONFIG_POSIX_CPU_TIMERS_TASK_WORK if supported
• Disable Bluetooth on devices where not operationally required
• Monitor for anomalous Bluetooth traffic and kernel panics
• Use EDR solutions with kernel-level telemetry on mobile endpoints

Detection Opportunities

• Bluetooth stack crashes or reboots
• Unexpected ACL packet patterns
• Privilege escalation attempts from Bluetooth-related processes

Incident Response Playbook: CVE-2025–48539

Phase 1: Identification

• Monitor kernel logs for acl_arbiter.cc anomalies
• Flag devices with unexplained reboots or Bluetooth stack failures
• Correlate with proximity-based device scans

Phase 2: Containment

• Isolate affected Android devices from Bluetooth networks
• Disable Bluetooth via MDM policies
• Block outbound traffic from suspected compromised devices

Phase 3: Eradication

• Apply kernel patches across all Android endpoints
• Reimage devices if exploitation is confirmed
• Rotate credentials and tokens stored on mobile devices

Phase 4: Recovery

• Restore Bluetooth functionality in controlled phases
• Validate kernel integrity and telemetry post-patch
• Resume normal operations with enhanced monitoring

Phase 5: Lessons Learned

• Review Bluetooth threat modelling
• Update mobile device hardening guides
• Conduct tabletop exercises simulating zero-click mobile exploits