Qualcomm Snapdragon GPU Driver Use-After-Free Vulnerability (CVE-2021-1905) Technical Analysis and Hardening Guide
Executive & SecOps Summary
SECOPS ASSESSMENTMultiple Qualcomm Snapdragon chipsets including Auto, Compute, Connectivity, Mobile, and Wearables
Local attackers can exploit improper memory mapping handling across multiple processes to achieve Use-After-Free (UAF), leading to Local Privilege Escalation (LPE) and kernel-level code execution
Apply the official security patches released by Qualcomm and device OEMs, and restrict unauthorized local process execution
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Because this is a hardware-level driver vulnerability, it must be resolved via system firmware updates provided by the device OEM. Ensure the Android Security Patch Level is dated May 2021 or later.
# Verify the current Android Security Patch Level via ADB
adb shell getprop ro.build.version.security_patch
# Ensure the output is '2021-05-01' or later.2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict local access vectors such as ADB and enforce strict application installation policies to prevent untrusted code execution.
# Disable ADB debugging to block local physical/network access vectors
adb shell settings put global adb_enabled 0
# Ensure SELinux is set to Enforcing mode to mitigate privilege escalation attempts
adb shell setenforce 1
adb shell getenforce3. Log Audit & IoC Verification Commands
Monitor system logs and kernel ring buffers for anomalies related to the KGSL driver or memory corruption events.
# Monitor logcat for KGSL driver errors and potential UAF indicators
adb logcat | grep -Ei 'kgsl|use-after-free|uaf|invalid memory'
# Search kernel dmesg logs for memory corruption or general protection faults
adb shell dmesg | grep -Ei 'use-after-free|general protection fault|kernel panic'Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-1905) is a Use-After-Free (UAF) flaw residing in the Qualcomm Graphics System Link (KGSL) GPU memory management driver. The root cause lies in the improper handling of simultaneous memory mapping requests from multiple processes. Due to inadequate synchronization or reference counting mechanisms during concurrent map/unmap operations, the driver fails to safely manage shared memory regions, leaving dangling pointers to freed memory blocks.
2. Exploitation Mechanics & Attack Scenario
An attacker with local non-privileged access executes a specially crafted multi-threaded application designed to trigger a race condition. By concurrently mapping and unmapping specific GPU memory regions, the attacker forces the kernel to free a memory page while the KGSL driver retains a reference to it. The attacker then reclaims this freed memory space with controlled data (such as kernel structures). When the driver subsequently accesses the dangling pointer, it triggers a Use-After-Free condition, allowing the attacker to corrupt kernel memory and escalate privileges to root.
3. Infrastructure & Business Impact
As a vulnerability listed in the CISA KEV catalog, this flaw has been actively exploited in the wild. It poses a severe threat to mobile devices, IoT gateways, and automotive infotainment systems (Snapdragon Auto). Successful exploitation compromises the entire operating system's integrity, enabling attackers to bypass sandbox restrictions, access sensitive user data, and establish persistent unauthorized access at the kernel level.
Official Vendor Advisories & References
Possible use after free due to improper handling of memory mapping of multiple processes simultaneously. in Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Consumer IOT, Snapdragon Industrial IOT, Snapdragon Mobile, Snapdragon Voice & Music, Snapdragon Wearables
Frequently Asked SecOps Questions (CVE-2021-1905)
FAQQ1. How critical is CVE-2021-1905 and is it actively exploited in the wild?
CVE-2021-1905 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 1.5%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-1905?
Primary impacted vendors include qualcomm across snapdragon_auto, snapdragon_compute, snapdragon_connectivity, snapdragon_consumer_iot, snapdragon_industrial_iot, snapdragon_mobile, snapdragon_voice_and_music, snapdragon_wearables. Scope summary: Devices powered by Qualcomm Snapdragon Auto, Compute, Connectivity, Consumer IOT, Industrial IOT, Mobile, Voice & Music, and Wearables chipsets
Q3. What temporary mitigations or workarounds exist for CVE-2021-1905 before patching?
[Mitigation] Apply the official security patches released by Qualcomm and device OEMs, and restrict unauthorized local process execution Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-1905
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
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