CVE-2025-21477 is a high-severity vulnerability identified in multiple Qualcomm Snapdragon platforms and related modem and connectivity products. The root cause is improper input validation (CWE-20) when processing CCCH (Common Control Channel) data, specifically when the network sends data with an invalid length. This improper validation can lead to a transient denial-of-service (DoS) condition. The CCCH is a critical channel used in cellular networks for control signaling between the mobile device and the network. When malformed or invalid length data is received, the affected Snapdragon components may crash or become unresponsive temporarily, disrupting normal device operation. The vulnerability affects a broad range of Qualcomm products, including many Snapdragon mobile platforms (from Snapdragon 4 Gen 1 up to Snapdragon 8+ Gen 2), various FastConnect Wi-Fi/Bluetooth modules, multiple modem-RF systems (X55, X62, X65, X70, X72, X75), and audio and connectivity chips (WCD and WSA series). The CVSS v3.1 base score is 7.5, indicating a high severity with network attack vector, low attack complexity, no privileges or user interaction required, and impact limited to availability (no confidentiality or integrity impact). There are no known exploits in the wild as of the published date (August 6, 2025), and no patches are currently linked, suggesting that mitigation may rely on vendor updates or network-level protections. This vulnerability could be triggered remotely by a malicious or misconfigured cellular network sending malformed CCCH data, causing devices using affected Qualcomm components to experience temporary service interruptions or crashes, impacting user experience and potentially critical communications.

For European organizations, the impact of CVE-2025-21477 can be significant, especially for sectors relying heavily on mobile connectivity and IoT devices using Qualcomm Snapdragon chipsets. The transient DoS could disrupt mobile communications, affecting voice, data, and IoT device availability. This is critical for emergency services, healthcare, transportation, and industrial control systems that depend on reliable cellular connectivity. Enterprises with mobile workforces or remote monitoring systems using affected devices may face operational interruptions. Although the vulnerability does not compromise confidentiality or integrity, the availability impact can lead to loss of productivity, service outages, and potential safety risks. Additionally, transient DoS conditions could be exploited as part of larger coordinated attacks to degrade network performance or cause cascading failures in critical infrastructure. Given the widespread use of Snapdragon platforms in smartphones, tablets, automotive systems, and IoT devices across Europe, the potential for disruption is broad. The lack of required privileges or user interaction means attackers could exploit this remotely without user awareness, increasing risk.

1. Immediate mitigation should focus on network-level protections: cellular network operators should implement strict validation and filtering of CCCH messages to prevent malformed data from reaching end devices. 2. Organizations should inventory and identify devices using affected Qualcomm Snapdragon components and monitor for unusual device reboots or connectivity interruptions. 3. Deploy network anomaly detection systems capable of identifying malformed signaling messages or unusual control channel traffic patterns. 4. Engage with device vendors and Qualcomm for timely firmware or software updates addressing this vulnerability once patches become available. 5. For critical deployments, consider fallback communication methods or redundant connectivity options to maintain availability during potential transient DoS events. 6. Educate IT and security teams about this vulnerability to enhance incident response readiness. 7. Where possible, apply configuration hardening on devices to limit exposure to untrusted networks or use VPNs and secure tunneling to reduce attack surface. 8. Collaborate with mobile network providers to ensure they are aware and actively mitigating risks associated with malformed CCCH data.