CVE-2025-21428: Snapdragon 439 Buffer Overflow Vulnerability

CVE-2025-21428 Overview

CVE-2025-21428 is a memory corruption vulnerability affecting numerous Qualcomm chipset firmware components. The vulnerability occurs during the process of connecting a station (STA) to an access point (AP) when an ADD TS (Traffic Specification) request is initiated from the AP to establish a TSpec session. This flaw in WLAN session handling can lead to denial of service conditions on affected devices.

Critical Impact

This vulnerability enables remote attackers to trigger memory corruption in WLAN firmware, potentially causing device crashes and denial of service across a wide range of Qualcomm-powered mobile devices, automotive platforms, IoT systems, and wireless connectivity modules.

Affected Products

• Qualcomm Snapdragon Mobile Platforms (210, 212, 425, 429, 439, 625, 626, 632 series)
• Qualcomm Snapdragon 820 Automotive Platform and Auto 5G Modem-RF
• Qualcomm FastConnect 6200 and 6900 Wi-Fi modules
• Qualcomm WCN series wireless connectivity chips (WCN3610, WCN3615, WCN3620, WCN3660B, WCN3680, WCN3680B, WCN3980)
• Qualcomm QCA series Wi-Fi chips (QCA6174, QCA6174A, QCA6574, QCA6584, QCA9377, and others)
• Qualcomm MDM series modems (MDM9250, MDM9628, MDM9640, MDM9650)
• Qualcomm Vision Intelligence 100/200 Platforms
• Qualcomm Smart Audio and Smart Display Platforms

Discovery Timeline

• April 7, 2025 - CVE-2025-21428 published to NVD
• October 6, 2025 - Last updated in NVD database

Technical Details for CVE-2025-21428

Vulnerability Analysis

This vulnerability is classified under CWE-126 (Buffer Over-read), indicating that the memory corruption occurs when the WLAN firmware reads data beyond the boundaries of allocated memory buffers during TSpec session establishment. The exploitation scenario involves a malicious or compromised access point sending specially crafted ADD TS requests to a connecting station, triggering the memory corruption condition.

The attack can be initiated remotely over the network without requiring authentication or user interaction, making it particularly dangerous in environments where devices connect to untrusted wireless networks. The primary impact is on availability, as successful exploitation leads to denial of service conditions rather than data compromise.

Root Cause

The root cause lies in improper buffer boundary validation within the WLAN firmware's TSpec session handling code. When processing ADD TS requests during the association phase between a station and an access point, the firmware fails to properly validate the length or boundaries of incoming data, resulting in a buffer over-read condition. This memory safety issue allows reading beyond allocated buffer boundaries, corrupting adjacent memory regions and destabilizing the wireless subsystem.

Attack Vector

The attack is network-based and can be executed by an attacker operating a malicious access point within wireless range of vulnerable devices. The attack sequence involves:

1. The attacker sets up a rogue access point that appears legitimate to target devices
2. When a vulnerable device attempts to connect to the malicious AP, the attacker initiates an ADD TS request
3. The crafted ADD TS request contains malformed data designed to trigger the buffer over-read
4. The WLAN firmware processes the request without proper bounds checking, causing memory corruption
5. The device experiences a denial of service condition, potentially requiring a reboot to recover

The vulnerability does not require the attacker to have any prior privileges or authentication, and no user interaction beyond connecting to the malicious network is needed.

Detection Methods for CVE-2025-21428

Indicators of Compromise

• Unexpected WLAN driver crashes or system instability when connecting to wireless networks
• Repeated firmware exceptions in Qualcomm WLAN subsystems logged in device crash reports
• Unusual ADD TS request patterns in wireless traffic captures near affected devices
• Device reboots or wireless connectivity failures during AP association attempts

Detection Strategies

• Monitor for abnormal ADD TS request frames in wireless network traffic using WLAN packet analysis tools
• Implement wireless intrusion detection systems (WIDS) to identify rogue access points sending malformed traffic
• Review device logs for WLAN driver crashes or kernel panics related to wireless connectivity
• Deploy network monitoring to detect suspicious access point behavior during client associations

Monitoring Recommendations

• Enable verbose logging on enterprise wireless controllers to capture TSpec-related events
• Implement alerting for multiple WLAN-related device crashes across your device fleet
• Monitor for unauthorized access points within your wireless environment
• Track firmware version status across Qualcomm-powered devices to identify unpatched systems

How to Mitigate CVE-2025-21428

Immediate Actions Required

• Apply firmware updates from device manufacturers that incorporate Qualcomm's security patches
• Avoid connecting affected devices to untrusted or public wireless networks until patched
• Configure enterprise wireless environments to detect and prevent rogue access points
• Review your device inventory to identify systems using affected Qualcomm chipsets

Patch Information

Qualcomm has addressed this vulnerability in their April 2025 Security Bulletin. Organizations should check with their device manufacturers (OEMs) for firmware updates that incorporate these security patches. The actual patch deployment depends on the device manufacturer's release schedule for specific device models.

Workarounds

• Restrict device connections to trusted, enterprise-managed wireless networks only
• Implement 802.1X authentication to prevent connections to rogue access points
• Enable wireless intrusion prevention features to automatically block suspicious APs
• Consider disabling Wi-Fi on affected devices when not actively required until patches are available

# Example: Check Qualcomm firmware version on Android devices via ADB
adb shell getprop ro.vendor.wlan.driver.version
adb shell getprop ro.hardware.wlan
# Review output against Qualcomm's April 2025 Security Bulletin for patch status