CVE-2025-21441: Qualcomm Fastconnect Use After Free Flaw

CVE-2025-21441 Overview

CVE-2025-21441 is a memory corruption vulnerability in the Qualcomm WLAN driver. The flaw is triggered when an IOCTL call is invoked from user-space to write board data into the driver. The condition is classified as an out-of-bounds write [CWE-787] and affects a wide range of Qualcomm FastConnect, QCA, WCD, WSA, and Snapdragon compute platform firmware components. Qualcomm addressed the issue in its April 2025 Security Bulletin.

Critical Impact
A local, low-privileged process on an affected device can corrupt kernel memory through the WLAN driver IOCTL interface, leading to loss of confidentiality, integrity, and availability of the affected system.

Affected Products

Qualcomm FastConnect 6200, 6700, 6800, 6900, and 7800 firmware
Qualcomm QCA-series chipsets (QCA1062/1064, QCA2062/2064/2065/2066, QCA6391, QCA6420, QCA6430) and QCC2073/QCC2076 firmware
Qualcomm Snapdragon 7c/7c Gen 2/7c+ Gen 3 and 8c/8cx compute platforms, QCM/QCS 5430/6490, SC8180X+SDX55, SC8380XP, SM6250, WCD/WSA audio codec firmware, and Video Collaboration VC3 platform firmware

Discovery Timeline

2025-04-07 - CVE-2025-21441 published to NVD
April 2025 - Qualcomm publishes fix in the April 2025 Security Bulletin
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21441

Vulnerability Analysis

The vulnerability resides in the Qualcomm WLAN driver path that handles board data writes initiated by user-space through an IOCTL request. When the driver processes the incoming buffer, it writes data outside the bounds of an allocated kernel structure. This out-of-bounds write [CWE-787] corrupts adjacent kernel memory. Exploitation is local and requires only low privileges on the device, but no user interaction. Successful exploitation can escalate privileges from an unprivileged process to the kernel context by overwriting sensitive data structures or function pointers reachable from the driver.

Root Cause

The root cause is inadequate validation of the size or contents of the user-supplied board data buffer passed to the WLAN driver through the IOCTL interface. Because the driver trusts the length or offset values provided by user-space, it writes beyond the intended kernel destination buffer.

Attack Vector

An attacker with local shell or code execution on an affected device opens the WLAN driver device node and issues the vulnerable IOCTL with a crafted board-data payload. The malformed request drives the out-of-bounds write inside the kernel driver. No network access and no user interaction are required. Attackers commonly reach this class of primitive from a compromised application sandbox to pivot toward full kernel compromise.

No public proof-of-concept exploit code is available for this issue. Technical details are limited to Qualcomm's advisory.

Detection Methods for CVE-2025-21441

Indicators of Compromise

Unexpected kernel panics, WLAN driver crashes, or dmesg entries citing memory corruption in Qualcomm WLAN modules on an affected Snapdragon or FastConnect platform.
Unprivileged processes opening WLAN driver device nodes and issuing IOCTLs that write board data, particularly outside of standard vendor tooling.
Sudden privilege changes or process context switches to root/kernel following WLAN driver interaction.

Detection Strategies

Monitor kernel logs for driver faults, KASAN reports, or oops messages referencing the Qualcomm WLAN driver and its board-data handlers.
Inventory endpoints and IoT devices to identify affected Qualcomm chipsets, then confirm they run firmware predating the April 2025 Qualcomm patch level.
On managed Android and Windows-on-Snapdragon fleets, track vendor security patch level (SPL) attestation and flag devices that have not received the April 2025 Qualcomm bulletin fixes.

Monitoring Recommendations

Correlate WLAN driver crash telemetry with process execution history to identify local processes triggering repeated abnormal IOCTL activity.
Alert on non-vendor binaries invoking WLAN driver ioctls, especially from application sandboxes or newly installed apps.
Track post-crash behavior such as new privileged processes, kernel module loads, or persistence artifacts that could indicate successful exploitation.

How to Mitigate CVE-2025-21441

Immediate Actions Required

Apply the firmware updates referenced in the Qualcomm April 2025 Security Bulletin to all affected devices.
Coordinate with OEMs (Android device manufacturers, Windows-on-Snapdragon vendors, IoT integrators) to obtain and deploy their downstream builds that incorporate the Qualcomm fix.
Restrict installation of untrusted applications on affected devices until the patched firmware is deployed, since exploitation requires local code execution.

Patch Information

Qualcomm has published a fix as part of the April 2025 Security Bulletin. Device vendors are expected to incorporate the update into their next security patch level. Verify remediation by confirming the device reports an April 2025 or later Qualcomm security patch level and by validating vendor-specific bulletins that reference CVE-2025-21441.

Workarounds

No vendor-supplied workaround is documented; patching is the required remediation path.
Where patching is delayed, limit local attack surface by enforcing application allow-listing and Mobile Device Management (MDM) policies that block untrusted app installation.
Enable SELinux/AppArmor enforcement and device-level exploit mitigations to raise the cost of chaining a local vulnerability into kernel compromise.

bash

# Verify Qualcomm security patch level on Android devices
adb shell getprop ro.vendor.build.security_patch
# Expected: 2025-04-01 or later once the fix is applied by the OEM