CVE-2026-56941: fpc_tee_hal.c Use-After-Free Vulnerability

CVE-2026-56941 Overview

CVE-2026-56941 is a use-after-free vulnerability in multiple functions of fpc_tee_hal.c, a Hardware Abstraction Layer (HAL) component used by the fingerprint Trusted Execution Environment (TEE) on affected Android devices. The flaw stems from a logic error that allows a freed memory object to be referenced again during subsequent operations. An attacker with local access can trigger the condition to achieve local escalation of privilege. No user interaction and no additional execution privileges are required. The issue is tracked in the Android Security Bulletin September 2026.

Critical Impact
Local attackers can escalate privileges on affected Android devices without user interaction, potentially compromising the confidentiality, integrity, and availability of the fingerprint TEE and the wider system.

Affected Products

Android devices shipping the fpc_tee_hal fingerprint HAL component
Pixel devices covered by the September 2026 Pixel security bulletin
Downstream Android OEM builds that integrate the same vendor HAL

Discovery Timeline

2026-09-15 - CVE-2026-56941 published to the National Vulnerability Database (NVD)
2026-09-17 - Entry last modified in NVD

Technical Details for CVE-2026-56941

Vulnerability Analysis

The vulnerability resides in fpc_tee_hal.c, the HAL implementation that brokers requests between Android userspace and the fingerprint Trusted Execution Environment. Multiple functions in the file mishandle the lifecycle of an internal object, freeing the underlying allocation while a stale pointer remains in use. Subsequent operations dereference that pointer, producing a use-after-free condition. Because the HAL runs with elevated privileges to communicate with the TEE, memory corruption at this layer directly translates into privileged control over TEE-mediated operations. The advisory categorizes the weakness under [CWE-693] (Protection Mechanism Failure), reflecting that the flaw undermines a security boundary rather than a simple memory bug in an unprivileged process.

Root Cause

The root cause is a logic error in object lifetime management within fpc_tee_hal.c. One code path releases a heap object while another retains a reference and continues to use it. The absence of consistent ownership tracking across the affected functions permits the stale reference to be dereferenced or reallocated with attacker-influenced content.

Attack Vector

Exploitation requires local access to the device, such as an installed application or a compromised process able to reach the fingerprint HAL. The attacker triggers the vulnerable sequence in fpc_tee_hal to corrupt memory and pivot into elevated context. User interaction is not required, and no additional privileges beyond local execution are needed. No public proof-of-concept and no confirmed in-the-wild exploitation are listed at publication.

No verified exploit code is available. Refer to the Android Security Bulletin September 2026 for vendor-supplied technical context.

Detection Methods for CVE-2026-56941

Indicators of Compromise

Unexpected crashes or tombstones referencing fpc_tee_hal or the fingerprint HAL service
Kernel or logcat entries showing repeated abnormal invocations of fingerprint HAL interfaces from non-system processes
Installation of untrusted applications shortly before privilege-related anomalies on the device

Detection Strategies

Monitor Android dropbox and tombstoned artifacts for SIGSEGV or SIGABRT signals in fingerprint HAL processes
Correlate SELinux denials targeting fingerprint HAL sockets or binder interfaces with process reputation data
Track deployed Android security patch levels across the fleet and flag devices below the September 2026 patch level

Monitoring Recommendations

Ingest mobile device management (MDM) telemetry into a centralized analytics platform to alert on missing patch levels
Alert on new sideloaded applications that request or interact with biometric APIs on unpatched devices
Review binder transaction logs on managed devices for anomalous callers to the fingerprint HAL

How to Mitigate CVE-2026-56941

Immediate Actions Required

Apply the September 2026 Android security patch level to all affected devices as soon as OEM builds are available
Prioritize patching for devices used by high-risk users, including administrators and executives
Restrict installation of untrusted applications through MDM policy until patches are deployed

Patch Information

The fix is delivered through the September 2026 Android security update. Google published details in the Android Security Bulletin September 2026, which lists the corrected fpc_tee_hal code and the associated patch level. Downstream OEMs must integrate the update into their device-specific builds before end users are protected.

Workarounds

Enforce application allowlists via MDM to reduce the attack surface reachable to the fingerprint HAL
Disable sideloading and restrict install sources to vetted enterprise or official stores
Retire or isolate devices that will not receive the September 2026 patch level

No vendor-supplied configuration workaround is published; patching is the authoritative remediation. Refer to the Android Security Bulletin September 2026 for device-specific patch guidance.