CVE-2025-21469: Qualcomm Fastconnect Use-After-Free Flaw

CVE-2025-21469 Overview

CVE-2025-21469 is a memory corruption vulnerability affecting Qualcomm chipset firmware across a wide range of FastConnect, QCM, QCS, WCD, and WSA product families. The flaw occurs when the image encoding path processes an IOCTL (Input/Output Control) call with an input buffer length of zero, resulting in an out-of-bounds write [CWE-787] and improper access control [CWE-284].

A local attacker with low privileges can trigger the condition to corrupt kernel memory, leading to loss of confidentiality, integrity, and availability on the affected device.

Critical Impact
Local, low-privileged attackers can corrupt memory in the image encoding driver on affected Qualcomm firmware, enabling potential privilege escalation and denial of service on mobile, compute, and IoT devices.

Affected Products

Qualcomm FastConnect 6700, 6900, and 7800 firmware
Qualcomm QCM5430, QCM6490, QCS5430, QCS6490, SC8380XP, SC8280XP-ABBB, Snapdragon 7c+ Gen 3 Compute, and Video Collaboration VC3 Platform firmware
Qualcomm WCD9370/9375/9380/9385 and WSA8830/8835/8840/8845/8845H audio codec and smart speaker amplifier firmware

Discovery Timeline

2025-05-06 - CVE-2025-21469 published to NVD
May 2025 - Qualcomm publishes the May 2025 Security Bulletin addressing the issue
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21469

Vulnerability Analysis

The vulnerability resides in the image encoding component reachable through an IOCTL interface exposed by Qualcomm firmware drivers. When a caller issues the IOCTL with an input buffer length set to zero, the encoding routine fails to correctly validate the length parameter before performing memory operations on the buffer.

The result is an out-of-bounds write condition classified under [CWE-787], compounded by an improper access control weakness [CWE-284] in the IOCTL handler. Corruption of adjacent kernel memory can lead to privilege escalation, kernel panic, or arbitrary code execution in the driver context.

The attack surface is broad because the affected firmware ships on Snapdragon compute platforms, mobile SoCs, Wi-Fi/Bluetooth combo chips, and audio codecs used in Android phones, laptops, and IoT devices.

Root Cause

The root cause is missing or insufficient length validation in the IOCTL handler that services image encoding requests. The handler proceeds to operate on the caller-supplied buffer descriptor even when the length is zero, causing the underlying memory routine to write outside the intended bounds.

Attack Vector

Exploitation requires local access to the device and low privileges sufficient to open the affected driver interface and issue IOCTL calls. No user interaction is required. A malicious application installed on an affected Android device, or a local user on a Snapdragon-based compute platform, could reach the vulnerable code path.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS probability for CVE-2025-21469 is 0.09%.

The vulnerability manifests when the driver dispatches a zero-length input buffer through its image encoding path without bounds enforcement. See the Qualcomm May 2025 Security Bulletin for vendor-supplied technical detail.

Detection Methods for CVE-2025-21469

Indicators of Compromise

Unexpected kernel panics, driver crashes, or reboots referencing the image encoding driver or IOCTL dispatch layer on affected Qualcomm firmware.
Applications with no legitimate media-processing purpose opening handles to encoder driver device nodes and issuing IOCTL calls.
Anomalous kernel log entries indicating out-of-bounds writes, corrupted heap metadata, or SELinux denials tied to media/encoding services.

Detection Strategies

Monitor Android application behavior for processes invoking IOCTLs against Qualcomm media/encoding device nodes with unusual parameter patterns, including zero-length input buffers.
Correlate device crash telemetry with recently installed or updated applications to identify local exploitation attempts.
Baseline firmware and driver versions across the fleet and alert on devices running Qualcomm firmware that predates the May 2025 patch level.

Monitoring Recommendations

Ingest Android system logs, dmesg output, and vendor debug logs from managed endpoints into a centralized logging pipeline for review of kernel-level anomalies.
Track the Android Security Patch Level (SPL) and OEM firmware versions on managed devices to confirm remediation coverage.
Alert on privilege escalation indicators such as new SELinux violations, unexpected root-owned processes, or capability changes following crashes in encoder-related components.

How to Mitigate CVE-2025-21469

Immediate Actions Required

Apply the firmware update from Qualcomm's May 2025 Security Bulletin, delivered through OEM and carrier updates for affected devices.
Inventory all devices containing the affected FastConnect, QCM, QCS, SC, Snapdragon Compute, WCD, and WSA components and verify their patch level.
Restrict installation of untrusted applications on affected Android and compute devices until firmware updates are deployed.

Patch Information

Qualcomm addressed CVE-2025-21469 in the Qualcomm May 2025 Security Bulletin. OEMs integrate the fix into their monthly Android security updates and platform firmware releases. Confirm patch adoption by checking that the device Android Security Patch Level or OEM firmware version aligns with the May 2025 or later release for the affected chipset family.

Workarounds

Enforce application allow-listing and mobile device management (MDM) policies that block installation of unverified applications capable of issuing IOCTLs to media drivers.
Reduce the local attack surface by disabling optional media-encoding features where the workload does not require them, if the OEM firmware exposes such controls.
Require prompt adoption of monthly Android security updates through MDM compliance policies to close the exposure window.

bash

# Verify Android Security Patch Level on a managed device
adb shell getprop ro.build.version.security_patch

# Confirm the reported patch level is 2025-05-01 or later