CVE-2026-21371: Qualcomm Aqt1000 Buffer Overflow Flaw

CVE-2026-21371 Overview

CVE-2026-21371 is a memory corruption vulnerability affecting Qualcomm firmware across a wide range of mobile platforms, compute platforms, and connectivity chipsets. The vulnerability occurs when retrieving an output buffer with insufficient size validation, which can lead to an out-of-bounds read condition (CWE-126). This type of vulnerability allows a local attacker with low privileges to potentially read sensitive memory contents, corrupt memory, or execute arbitrary code on affected devices.

Critical Impact

A local attacker can exploit this memory corruption flaw to achieve confidentiality, integrity, and availability compromise on affected Qualcomm-powered devices including smartphones, laptops, and IoT equipment.

Affected Products

• Qualcomm Snapdragon 8cx Gen 3 Compute Platform and earlier generations
• Qualcomm FastConnect 6200/6700/6800/6900/7800 series firmware
• Qualcomm Snapdragon 460/662 Mobile Platform firmware
• Qualcomm WCD9340/9341/9370/9375/9378c/9380/9385 Audio Codec firmware
• Qualcomm WSA8810/8815/8830/8835/8840/8845/8845H Smart Amplifier firmware
• Qualcomm QCA6391/6420/6430 and QCM5430/6490 Platform firmware
• Qualcomm Video Collaboration VC3 Platform firmware

Discovery Timeline

• April 6, 2026 - CVE-2026-21371 published to NVD
• April 8, 2026 - Last updated in NVD database

Technical Details for CVE-2026-21371

Vulnerability Analysis

This vulnerability stems from improper buffer size validation when handling output buffer retrieval operations in Qualcomm firmware components. The flaw is classified as CWE-126 (Buffer Over-read), indicating that the affected code reads data beyond the intended boundaries of a buffer. When a function attempts to retrieve data into an output buffer, it fails to properly validate whether the destination buffer is sufficiently sized to hold the incoming data.

The exploitation requires local access to the device, meaning an attacker would need to have some level of existing access—either through a malicious application installed on the device or through physical access. Once exploited, the vulnerability can lead to unauthorized disclosure of sensitive information stored in adjacent memory regions, potential memory corruption affecting system stability, or in severe cases, arbitrary code execution if the memory corruption can be leveraged to overwrite critical data structures or function pointers.

Root Cause

The root cause is insufficient size validation when copying data to an output buffer. The firmware code fails to verify that the destination buffer has adequate capacity before performing the copy operation. This missing bounds check allows reads beyond the allocated buffer size, triggering an out-of-bounds memory access condition.

Attack Vector

The attack vector for CVE-2026-21371 is local, requiring an attacker to have authenticated access to the target device. Exploitation does not require user interaction and can be accomplished with low-privilege access. A malicious application running on an affected device could invoke the vulnerable firmware function with crafted parameters to trigger the buffer over-read.

The attack scenario typically involves:

1. An attacker gains local access to a device running vulnerable Qualcomm firmware
2. The attacker invokes the vulnerable function through available interfaces
3. By providing specific parameters that cause insufficient buffer allocation, the attacker triggers the out-of-bounds read
4. Memory contents beyond the intended buffer boundaries are disclosed or corrupted

Detection Methods for CVE-2026-21371

Indicators of Compromise

• Unexpected system crashes or kernel panics on Qualcomm-based devices that may indicate memory corruption exploitation attempts
• Unusual process behavior or memory access patterns in firmware-related components
• Application crashes with memory access violation errors related to audio or connectivity subsystems

Detection Strategies

• Monitor system logs for firmware-related errors or crashes on Qualcomm chipsets, particularly in audio codec (WCD) or wireless connectivity (WCN/QCA) components
• Implement endpoint detection solutions that can identify anomalous memory access patterns at the kernel level
• Deploy SentinelOne Singularity agents on ARM-based Windows devices using Snapdragon compute platforms for behavioral analysis and exploit detection

Monitoring Recommendations

• Enable verbose logging for device drivers associated with affected Qualcomm components
• Monitor for signs of privilege escalation following suspicious application activity on mobile or compute devices
• Establish baseline behavior for firmware components and alert on deviations

How to Mitigate CVE-2026-21371

Immediate Actions Required

• Review the Qualcomm Security Bulletin April 2026 for detailed remediation guidance
• Apply firmware updates from device OEMs as they become available
• Restrict installation of untrusted applications on affected devices to reduce local attack surface
• Implement mobile device management (MDM) policies to enforce security updates

Patch Information

Qualcomm has disclosed this vulnerability in their April 2026 Security Bulletin. Device manufacturers utilizing affected Qualcomm chipsets are responsible for delivering firmware updates to end users. Organizations should coordinate with their device vendors to obtain patched firmware versions.

For detailed patch information and affected component versions, refer to the Qualcomm Security Bulletin April 2026.

Workarounds

• Limit application installation to trusted sources (official app stores) to reduce the risk of malicious local applications exploiting this vulnerability
• Implement application allowlisting on enterprise devices to prevent unauthorized code execution
• Enable device encryption and secure boot features to limit the impact of potential exploitation
• Segment network access for devices running vulnerable firmware until patches can be applied

# Example: Android device firmware version check
adb shell getprop ro.build.fingerprint
adb shell getprop ro.board.platform
# Verify device platform matches affected Qualcomm chipsets
# Contact OEM for patch availability timeline