Mbed TLS CVE-2026-34871

The vulnerability resides in the PRNG implementation used by Mbed TLS and TF-PSA-Crypto for generating cryptographic random numbers, which are fundamental to key generation, nonce creation, and other security-critical operations. The root cause involves predictable seed initialization-the mechanism that initializes the PRNG state lacks sufficient entropy or uses a deterministic source rather than a cryptographically secure random source. Since PRNG output directly feeds cryptographic operations including RSA/ECDSA signatures, symmetric cipher initialization, and protocol handshakes, a predictable seed undermines the security guarantees of all downstream cryptographic operations. This affects the C/C++ implementations of both Mbed TLS (a widely-used embedded TLS library) and TF-PSA-Crypto (the ARM Platform Security Architecture cryptography API), which are used extensively in embedded systems, IoT devices, mobile platforms, and other resource-constrained environments.