CVE-2023-21671 Overview
CVE-2023-21671 is a memory corruption vulnerability affecting Qualcomm Core firmware. The flaw occurs during a syscall handler used by the Sectools Fuse comparison feature. A local authenticated attacker can trigger the condition to corrupt kernel memory and gain elevated privileges on the device. The issue impacts a broad range of Qualcomm Snapdragon mobile platforms, FastConnect modules, audio codecs, and connectivity chipsets. Qualcomm addressed the defect in the November 2023 security bulletin. The weakness is categorized as improper input validation [CWE-20].
Critical Impact
Successful exploitation yields full confidentiality, integrity, and availability impact on the affected firmware, enabling local privilege escalation across millions of Snapdragon-based devices.
Affected Products
- Qualcomm Snapdragon 888 / 888+ 5G Mobile Platform firmware
- Qualcomm Snapdragon 778G / 778G+ / 780G / 782G 5G Mobile Platform firmware
- Qualcomm FastConnect 6700/6900, QCA6391, QCM6490, QCS6490, QSM8350, WCN6740, WCD937x/938x, and WSA883x firmware
Discovery Timeline
- 2023-11-07 - CVE-2023-21671 published to NVD
- 2025-08-11 - Last updated in NVD database
Technical Details for CVE-2023-21671
Vulnerability Analysis
The vulnerability resides in the Qualcomm Core component responsible for handling syscalls associated with the Sectools Fuse comparison feature. Sectools is the Qualcomm secure-boot tooling suite that interacts with hardware fuses to validate signed images and configuration data. When a privileged user-space process invokes the syscall path tied to fuse comparison, insufficient validation of attacker-controlled parameters allows the kernel handler to write outside intended memory boundaries. The resulting memory corruption can be steered to overwrite control structures, providing a path to arbitrary code execution within a privileged context.
Root Cause
The defect is an improper input validation flaw [CWE-20] in the syscall interface. Parameters passed from user space are consumed by the fuse comparison logic without rigorous bounds and type checking. This permits malformed sizes, lengths, or pointers to corrupt adjacent memory regions during processing.
Attack Vector
Exploitation requires local code execution with low privileges on the device. The attacker invokes the vulnerable syscall with crafted arguments to trigger the memory corruption primitive. No user interaction is required. Because the vulnerable code path executes in a privileged context, successful exploitation enables elevation beyond the application sandbox toward kernel or trusted execution components.
No public proof-of-concept code is available for CVE-2023-21671. See the Qualcomm November 2023 Bulletin for technical advisory details.
Detection Methods for CVE-2023-21671
Indicators of Compromise
- Unexpected kernel panics, crashes, or reboot loops on Snapdragon-based devices referencing the Sectools or fuse comparison code paths.
- Unsigned or unexpected native binaries invoking low-level Qualcomm driver ioctls or syscalls outside normal vendor processes.
- Logcat or dmesg entries showing access violations or SIGSEGV in privileged Qualcomm components.
Detection Strategies
- Monitor mobile device management (MDM) telemetry for devices running firmware older than the November 2023 Qualcomm patch level.
- Inspect installed Android applications for those requesting native access to Qualcomm hardware interfaces without justification.
- Correlate device crash reports across the fleet to identify abnormal clustering on Snapdragon SoCs.
Monitoring Recommendations
- Ingest Android security patch level (SPL) attestation results into your SIEM and alert on devices below the November 2023 baseline.
- Track Qualcomm vendor bulletins and OEM patch propagation to validate fleet-wide remediation status.
- Enable Play Protect and OEM threat detection signals to surface anomalous local privilege escalation attempts.
How to Mitigate CVE-2023-21671
Immediate Actions Required
- Apply the November 2023 (or later) Android Security Patch Level supplied by your device OEM.
- Inventory all Snapdragon-based devices across mobile, IoT, and compute fleets to confirm patch availability.
- Restrict installation of untrusted applications that could supply the local code execution prerequisite.
Patch Information
Qualcomm published fixes in the Qualcomm November 2023 Security Bulletin. OEM device manufacturers must integrate Qualcomm's patched firmware into their respective Android security patch releases. Confirm remediation by validating the device security patch level reflects November 2023 or later.
Workarounds
- No vendor-supplied workaround exists; firmware update is the only effective remediation.
- Enforce MDM policies blocking sideloaded applications and restricting developer mode on managed devices.
- Retire or isolate end-of-life devices that will not receive the November 2023 firmware update from the OEM.
# Verify Android Security Patch Level on managed devices
adb shell getprop ro.build.version.security_patch
# Expected output: 2023-11-01 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
