CVE-2025-21434: Qualcomm Qcs8300 Firmware DOS Vulnerability

CVE-2025-21434 Overview

CVE-2025-21434 is a denial of service vulnerability affecting multiple Qualcomm chipset firmware components. The vulnerability exists in the Wi-Fi subsystem's handling of Extremely High Throughput (EHT) Information Elements (IEs), specifically during the parsing of EHT operation IE or EHT capability IE. EHT is the core technology behind Wi-Fi 7 (802.11be), and improper handling of these protocol elements can cause a transient denial of service condition on affected devices.

Critical Impact

Network-accessible denial of service vulnerability affecting Wi-Fi functionality across numerous Qualcomm mobile, automotive, IoT, and networking chipsets without requiring authentication or user interaction.

Affected Products

• Qualcomm Snapdragon 8 Gen 2/3 Mobile Platforms and firmware
• Qualcomm FastConnect 6700/6900/7800 Wi-Fi chipsets and firmware
• Qualcomm SA8155P/SA8195P/SA8775P Automotive Platforms and firmware
• Qualcomm WCN7750/WCN7860/WCN7880 series Wi-Fi connectivity chipsets
• Qualcomm QCA6574/QCA6595/QCA6696 series chipsets and firmware

Discovery Timeline

• April 7, 2025 - CVE-2025-21434 published to NVD
• October 6, 2025 - Last updated in NVD database

Technical Details for CVE-2025-21434

Vulnerability Analysis

This vulnerability is classified as CWE-126 (Buffer Over-read), indicating that the affected firmware reads data past the end of an intended buffer when parsing EHT Information Elements. In Wi-Fi 7 networks, EHT operation IE and EHT capability IE are management frame elements that convey critical information about the network's operational parameters and device capabilities.

When a vulnerable Qualcomm device receives malformed or specially crafted EHT IEs during Wi-Fi scanning, association, or beaconing processes, the parsing routine may attempt to read beyond allocated memory boundaries. This over-read condition causes the Wi-Fi subsystem to enter an unstable state, resulting in a transient denial of service condition. The "transient" nature indicates the device can typically recover after the attack traffic ceases or upon service restart.

The vulnerability can be triggered remotely over the network without requiring any authentication or user interaction. An attacker within Wi-Fi range could broadcast malicious beacon frames or respond to probe requests with crafted EHT IEs to trigger the condition on nearby vulnerable devices.

Root Cause

The root cause is insufficient bounds checking in the EHT IE parsing code within the Wi-Fi firmware. When processing EHT operation or capability Information Elements, the parser fails to properly validate the length field against the actual data available in the buffer. This allows the parsing routine to read beyond the allocated memory when processing maliciously crafted IEs with inconsistent length fields or truncated data.

Attack Vector

The attack can be executed by an adversary with proximity to the target device over a Wi-Fi network. The attacker can craft malicious 802.11be management frames containing specially constructed EHT operation IE or EHT capability IE fields. These frames can be delivered through:

1. Rogue Access Point: Broadcasting beacon frames with malformed EHT IEs
2. Probe Response Injection: Responding to victim probe requests with crafted responses
3. Frame Injection: Injecting malicious frames during the association process

The attack requires no authentication, no user interaction, and can affect any device within wireless range that is actively scanning or connected to Wi-Fi 7 networks.

Detection Methods for CVE-2025-21434

Indicators of Compromise

• Repeated Wi-Fi subsystem crashes or service restarts in system logs
• Unexplained Wi-Fi disconnections or inability to maintain stable connections
• Kernel panic or watchdog timeout events related to WLAN drivers
• Anomalous 802.11be beacon or probe response frames in wireless traffic captures

Detection Strategies

• Monitor system logs for WLAN driver crashes, firmware resets, or EHT-related parsing errors
• Implement wireless intrusion detection to identify malformed 802.11be management frames
• Track Wi-Fi service availability metrics and alert on abnormal restart patterns
• Analyze captured wireless traffic for EHT IEs with inconsistent or invalid length fields

Monitoring Recommendations

• Enable detailed logging for Wi-Fi firmware events on affected devices
• Deploy wireless monitoring solutions capable of 802.11be frame analysis
• Configure alerting for unusual Wi-Fi subsystem behavior patterns in fleet management tools
• Establish baseline metrics for Wi-Fi stability to detect degradation from exploitation attempts

How to Mitigate CVE-2025-21434

Immediate Actions Required

• Apply firmware updates from Qualcomm or device OEMs as they become available
• Review the Qualcomm April 2025 Security Bulletin for specific patch information
• Inventory all devices containing affected Qualcomm chipsets in your environment
• Prioritize patching for devices in high-risk or public-facing wireless environments

Patch Information

Qualcomm has disclosed this vulnerability in their April 2025 Security Bulletin. Organizations should contact their device OEMs for specific firmware update availability and installation procedures. The bulletin provides detailed information about affected chipsets and recommended remediation steps at the Qualcomm Security Bulletin page.

Workarounds

• Where possible, disable Wi-Fi 7 (802.11be) mode and operate in Wi-Fi 6E or earlier modes until patches are applied
• Implement network segmentation to isolate affected IoT and automotive devices
• Use wired connections for critical systems where Wi-Fi connectivity is not essential
• Monitor for and block suspicious wireless activity in controlled environments using wireless intrusion prevention systems

# Example: Check device firmware version on Android devices with adb
adb shell getprop ro.vendor.qti.version.firmware
adb shell getprop ro.build.version.security_patch