CVE-2026-21373: Qualcomm Aqt1000 Buffer Overflow Flaw

CVE-2026-21373 Overview

CVE-2026-21373 is a memory corruption vulnerability affecting Qualcomm firmware across multiple chipset families, including Snapdragon mobile and compute platforms, FastConnect Wi-Fi modules, and various audio codec components. The vulnerability occurs when an output buffer is accessed without proper validation of its size during IOCTL (Input/Output Control) processing, potentially allowing a local attacker to achieve code execution or escalate privileges on affected devices.

Critical Impact

A local attacker with low privileges can exploit this memory corruption vulnerability to potentially achieve full compromise of affected Qualcomm-based devices, impacting confidentiality, integrity, and availability.

Affected Products

• Qualcomm Snapdragon 8cx Gen 3 Compute Platform Firmware
• Qualcomm FastConnect 6200/6700/6800/6900/7800 Firmware
• Qualcomm Snapdragon 460/662 Mobile Platform Firmware
• Qualcomm Snapdragon 7c/7c Gen 2/7c+ Gen 3 Compute Platform Firmware
• Qualcomm WCD9340/WCD9341/WCD9370/WCD9375/WCD9380/WCD9385 Audio Codec Firmware
• Qualcomm QCA6391/QCA6420/QCA6430 Wi-Fi Module Firmware
• Qualcomm SM6250 and SC8380XP Platform Firmware

Discovery Timeline

• April 6, 2026 - CVE-2026-21373 published to NVD
• April 8, 2026 - Last updated in NVD database

Technical Details for CVE-2026-21373

Vulnerability Analysis

This vulnerability represents a buffer over-read condition (CWE-126) within the IOCTL processing mechanism of affected Qualcomm firmware. IOCTL calls are a fundamental interface between user-space applications and kernel-mode drivers, commonly used for device configuration and data transfer operations. When processing these calls, the firmware fails to properly validate the size of the output buffer before accessing it, leading to memory corruption.

The flaw requires local access and low privileges to exploit, but does not require user interaction. Successful exploitation can result in complete compromise of the affected system, allowing an attacker to read or write arbitrary memory locations, execute arbitrary code with elevated privileges, or crash the device.

Root Cause

The root cause of CVE-2026-21373 is improper input validation in the IOCTL handler code path. Specifically, the firmware accesses an output buffer provided by user-space code without first verifying that the buffer size is adequate for the data being written. This represents a classic buffer over-read vulnerability where the code reads beyond the allocated buffer boundaries.

In typical IOCTL implementations, the driver should validate both input and output buffer lengths against expected values before performing any operations. The absence of this validation allows malformed IOCTL requests to trigger out-of-bounds memory access.

Attack Vector

The attack requires local access to the vulnerable device. An attacker would need to:

1. Gain initial access to the device with low-privilege user permissions
2. Craft a malicious IOCTL request with a deliberately undersized output buffer
3. Issue the IOCTL call to trigger the buffer over-read condition
4. Leverage the memory corruption to achieve code execution or privilege escalation

The vulnerability is particularly concerning for mobile devices and compute platforms where malicious applications might exploit this flaw to escape sandbox restrictions or elevate privileges to kernel level.

Detection Methods for CVE-2026-21373

Indicators of Compromise

• Unexpected system crashes or kernel panics on affected Qualcomm-based devices
• Suspicious IOCTL activity patterns in driver-level logging
• Evidence of memory corruption artifacts in crash dumps
• Abnormal process behavior indicating potential privilege escalation

Detection Strategies

• Monitor for anomalous driver communication patterns using endpoint detection and response (EDR) solutions
• Implement kernel-level integrity monitoring to detect unauthorized memory modifications
• Deploy SentinelOne's behavioral AI engine to identify exploitation attempts targeting driver interfaces
• Review system logs for repeated driver crashes that may indicate exploitation attempts

Monitoring Recommendations

• Enable comprehensive driver and IOCTL logging on systems with affected Qualcomm components
• Implement SentinelOne Singularity Platform for real-time detection of memory corruption exploitation
• Monitor for unusual process privilege changes that could indicate successful exploitation
• Track firmware update status across all affected devices in your environment

How to Mitigate CVE-2026-21373

Immediate Actions Required

• Apply firmware updates from Qualcomm as documented in the April 2026 Security Bulletin
• Inventory all devices containing affected Qualcomm chipsets to prioritize patching
• Restrict local access to affected devices where possible until patches are applied
• Implement application allowlisting to prevent unauthorized code execution

Patch Information

Qualcomm has released security patches addressing this vulnerability in their April 2026 Security Bulletin. Organizations should consult their device manufacturers (OEMs) for device-specific firmware updates, as patches are typically distributed through OEM update channels rather than directly from Qualcomm. The patch addresses the buffer validation issue by implementing proper size checks before accessing the output buffer in IOCTL handlers.

Refer to the Qualcomm April 2026 Security Bulletin for the complete list of affected components and patch availability.

Workarounds

• Limit local access to devices with affected Qualcomm components to trusted users only
• Implement strict application control policies to prevent unauthorized applications from making driver calls
• Deploy network segmentation to isolate potentially vulnerable devices
• Monitor for exploitation attempts using SentinelOne's endpoint protection capabilities

# Check for affected Qualcomm components on Android devices
adb shell getprop ro.board.platform
# Monitor IOCTL activity (requires root)
adb shell dmesg | grep -i "ioctl"