CVE-2026-6924 in Matter
Summary
by MITRE • 07/24/2026
A bug in the entropy initialization for SiWx917 causes the DRBG to use a predictable seed. As such, all random numbers generated in the Matter code use the same stream of numbers. This vulnerability was discovered after the impacted repository was already deprecated.
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Analysis
by VulDB Data Team • 07/24/2026
The vulnerability in question affects the Silicon Laboratories SiWx917 wireless SoC and specifically impacts the Deterministic Random Bit Generator implementation within the Matter protocol stack. This represents a critical cryptographic weakness that fundamentally undermines the security guarantees of random number generation in IoT devices. The issue stems from improper entropy initialization during the device boot process, which results in the DRBG algorithm receiving a static or predictably seeded value rather than truly random data.
The technical flaw manifests as a failure in the cryptographic initialization routine where the entropy source fails to provide sufficient unpredictability to seed the DRBG. According to CWE-330, this constitutes an insufficient entropy problem where the randomness pool does not contain adequate entropy for cryptographic operations. The predictable seeding means that all subsequent random number generation follows identical sequences, effectively breaking the fundamental security assumptions of cryptographic protocols that rely on unpredictable values.
The operational impact of this vulnerability is severe and far-reaching across multiple security domains within IoT ecosystems. When Matter protocol implementations use predictable random numbers, it compromises session key generation, nonce creation, and cryptographic token issuance that are essential for secure device communication. This weakness creates a pathway for attackers to potentially predict cryptographic operations, forge authentication tokens, or break encryption schemes that depend on the randomness properties of the underlying implementation. The vulnerability affects all devices using the deprecated SiWx917 repository, making it particularly concerning given the widespread deployment of Matter-compatible IoT solutions.
Security frameworks such as the ATT&CK framework categorize this issue under privilege escalation and credential access patterns, where predictable random number generation enables adversaries to bypass authentication mechanisms and gain unauthorized access to secure communications. The vulnerability represents a failure in the cryptographic implementation phase and demonstrates poor adherence to security best practices for entropy management. Organizations should immediately disable any affected devices and implement proper entropy sources that meet minimum cryptographic strength requirements. Mitigation strategies include replacing the affected hardware components, updating firmware with proper entropy initialization routines, and implementing additional security layers such as device attestation protocols that can detect and isolate compromised devices within the network infrastructure.
The discovery of this vulnerability after the repository was deprecated highlights significant gaps in the security lifecycle management for IoT device development, particularly regarding post-release security monitoring and remediation processes. This situation underscores the importance of maintaining security posture even for deprecated systems and demonstrates how seemingly minor implementation flaws can have catastrophic consequences in cryptographic contexts where predictability undermines entire security architectures.