CVE-2025-21461: Qualcomm Fastconnect Use-After-Free Flaw

CVE-2025-21461 Overview

CVE-2025-21461 is a memory corruption vulnerability affecting multiple Qualcomm chipsets and firmware components. The flaw occurs when programming registers through the virtual Camera Data Mover (CDM) interface. Qualcomm disclosed the issue in the August 2025 Security Bulletin, covering platforms such as Snapdragon 8 Gen 1, Snapdragon 8 Gen 3, FastConnect 6900/7800, and multiple WCD, WCN, and WSA audio and connectivity components. The vulnerability is classified under [CWE-787] (Out-of-Bounds Write) and requires local access with low privileges to exploit.

Critical Impact
A local, low-privileged attacker can trigger memory corruption through the virtual CDM interface, resulting in loss of confidentiality, integrity, and availability on affected Qualcomm chipsets.

Affected Products

Qualcomm Snapdragon 8 Gen 1 and Snapdragon 8 Gen 3 Mobile Platforms
Qualcomm FastConnect 6900 and FastConnect 7800
Qualcomm WCD937x/WCD938x/WCD939x, WSA883x/WSA884x, WCN665x, and SM66xx/SM76xx/SM86xx firmware

Discovery Timeline

2025-08-06 - CVE-2025-21461 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21461

Vulnerability Analysis

The vulnerability resides in the register-programming path exposed through the virtual Camera Data Mover (CDM) interface within Qualcomm firmware. The virtual CDM allows software to queue register writes that the hardware later executes to configure imaging and multimedia pipelines. Insufficient validation of caller-supplied register data or offsets leads to an out-of-bounds write into adjacent memory structures.

Memory corruption in this code path can be leveraged for privilege escalation because the CDM operates in a trust boundary that services higher-privileged multimedia and connectivity subsystems. Successful exploitation compromises confidentiality, integrity, and availability of the affected component.

Root Cause

The root cause is an out-of-bounds write [CWE-787] triggered when the virtual CDM programs registers using attacker-influenced input. Missing or incorrect bounds checks on the register index, offset, or payload length allow writes beyond the intended buffer or register window, corrupting adjacent memory.

Attack Vector

Exploitation requires local access to the device and low-privilege execution, such as an installed application able to reach the affected driver or IOCTL interface exposed to userspace. No user interaction is required. An attacker with a foothold on the device can submit crafted register-programming requests to the virtual CDM to corrupt memory and pivot toward code execution in a higher-privileged context.

No public proof-of-concept exploit code is available for this issue. Refer to the Qualcomm August 2025 Security Bulletin for vendor-authored technical context.

Detection Methods for CVE-2025-21461

Indicators of Compromise

Unexpected kernel or firmware panics referencing camera, CDM, or multimedia driver modules on affected Qualcomm chipsets.
Applications with no legitimate camera or multimedia function issuing frequent IOCTL calls to CDM-related device nodes.
Anomalous audio/connectivity subsystem crashes on WCD, WCN, or WSA components correlated with third-party app activity.

Detection Strategies

Monitor mobile device management (MDM) telemetry for firmware/OS build strings that do not include the August 2025 Qualcomm patch level.
Baseline installed applications against those that legitimately require access to camera or multimedia device nodes; investigate deviations.
Correlate repeated device reboots or SELinux denials involving Qualcomm multimedia drivers with recent app installations.

Monitoring Recommendations

Ingest mobile endpoint logs, MDM compliance reports, and crash telemetry into a centralized data lake for cross-device correlation.
Track Qualcomm security bulletin patch levels across the mobile fleet and flag devices lagging behind current baselines.
Alert on installation of unsigned or side-loaded applications on devices that hold sensitive corporate data.

How to Mitigate CVE-2025-21461

Immediate Actions Required

Apply the OEM firmware update that incorporates Qualcomm's August 2025 security patch level as soon as it is released for your device model.
Inventory all mobile devices and embedded systems using the affected Snapdragon, FastConnect, WCD, WCN, WSA, and SM-series components.
Restrict installation of untrusted third-party applications on affected devices through MDM policy.

Patch Information

Qualcomm addressed CVE-2025-21461 in its August 2025 Security Bulletin. Fixes are delivered to end users through OEM firmware updates. Contact your device manufacturer for the specific build that includes the August 2025 Qualcomm patch level.

Workarounds

No vendor-supplied workaround exists; patching through OEM firmware updates is the required remediation path.
As a compensating control, enforce application allowlisting and block installation of applications from untrusted sources via MDM.
Isolate unpatched devices from sensitive networks and data until firmware updates are available and deployed.

bash

# Verify Android security patch level on managed devices
adb shell getprop ro.build.version.security_patch

# Example MDM compliance check: require August 2025 patch level or later
# Non-compliant devices should be quarantined until updated