CVE-2026-2815 in SiSDK
Summary
by MITRE • 06/25/2026
Incorrect use of the PUF key for user key generation in EFR32xG27 results in predictable keys
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Analysis
by VulDB Data Team • 06/25/2026
The vulnerability involves improper utilization of the Physical Unclonable Function (PUF) key within the EFR32xG27 wireless microcontroller family, leading to predictability in generated user keys. This flaw fundamentally compromises the security foundation of cryptographic operations that rely on PUF-derived secrets for key generation processes. The PUF mechanism is designed to provide unique and unpredictable cryptographic material based on physical manufacturing variations, but when incorrectly implemented for user key derivation, it fails to maintain the essential properties of uniqueness and unpredictability required for secure cryptographic operations. The vulnerability specifically affects devices where the PUF output is not properly processed or mixed with sufficient entropy sources during the key generation algorithm implementation.
The technical flaw manifests in the cryptographic implementation where the raw PUF output is directly used or inadequately transformed for user key generation without proper cryptographic mixing or entropy augmentation. This approach violates fundamental security principles that require multiple entropy sources and proper cryptographic processing to ensure key unpredictability. The vulnerability creates a scenario where attackers can potentially reconstruct or predict user keys by analyzing the PUF behavior, effectively undermining the entire cryptographic security model. When PUF outputs are used directly for key derivation without proper hashing, stretching, or mixing operations, the resulting keys become susceptible to various attacks including brute force attempts, pattern recognition, and statistical analysis. This represents a critical failure in the cryptographic implementation that can be exploited across multiple attack vectors.
The operational impact of this vulnerability extends beyond simple key predictability, as it affects the entire security posture of devices relying on EFR32xG27 for wireless communications and secure data handling. Devices using affected microcontrollers may experience compromised encryption integrity, unauthorized access to encrypted data, and potential system takeover scenarios where attackers can impersonate legitimate users or devices within the network. The vulnerability particularly impacts applications in IoT deployments, industrial control systems, and security-critical environments where device authentication and data protection are paramount. Organizations relying on these microcontrollers for secure communications may face significant risk exposure including data breaches, unauthorized device control, and potential cascading security failures throughout connected networks. The predictability of keys undermines the core security assumptions that enable secure wireless communication protocols and cryptographic authentication mechanisms.
Mitigation strategies should focus on implementing proper cryptographic key derivation functions that incorporate multiple entropy sources and ensure adequate mixing of PUF outputs with additional randomization techniques. Security patches should be developed to replace direct PUF usage with standardized key derivation approaches such as PBKDF2, HKDF, or other established cryptographic protocols that properly handle PUF outputs through appropriate hashing and stretching mechanisms. Organizations must conduct comprehensive security assessments of their deployed devices to identify systems affected by this vulnerability and implement firmware updates that correct the PUF usage patterns. The remediation process should include proper entropy injection from multiple sources, implementation of cryptographic key derivation functions that meet industry standards, and validation procedures to ensure that generated keys maintain appropriate entropy levels for secure cryptographic operations. This vulnerability aligns with CWE-330, which addresses insufficient entropy, and may be mapped to ATT&CK techniques related to credential access and privilege escalation through predictable cryptographic material exploitation.
The root cause of this issue stems from inadequate understanding of PUF characteristics and their proper integration into cryptographic systems. Modern security frameworks emphasize the importance of combining multiple entropy sources and implementing robust key derivation processes that can handle the inherent variability of physical unclonable functions. The vulnerability demonstrates the critical need for comprehensive security testing of cryptographic implementations and adherence to established security standards such as NIST SP 800-57 for key management practices. Proper implementation requires careful consideration of PUF output characteristics, including their statistical properties and potential predictability issues, along with appropriate cryptographic processing to ensure that derived keys maintain the required security properties for their intended applications. Organizations should establish robust testing procedures that validate the entropy quality of generated keys and verify that cryptographic implementations properly leverage PUF mechanisms without compromising overall system security.