CVE-2022-46392 is a cryptographic vulnerability affecting Mbed TLS versions prior to 2.28.2 and 3.x versions before 3.3.0. The flaw arises in the RSA private key exponentiation process when the window size parameter (MBEDTLS_MPI_WINDOW_SIZE) is set to 3 or smaller. An attacker with the capability to monitor memory access patterns with high precision—typically an untrusted operating system targeting a secure enclave—can exploit this side-channel leakage to recover the victim's RSA private key after observing just a single private-key operation. This attack leverages the correlation between the exponentiation algorithm's memory access patterns and the secret key bits, effectively breaking the confidentiality of the RSA private key. The vulnerability is particularly relevant in environments where secure enclaves or trusted execution environments (TEEs) rely on Mbed TLS for cryptographic operations but run atop potentially compromised or malicious operating systems. The CVSS v3.1 base score is 5.3 (medium severity), reflecting the network attack vector, high attack complexity, no privileges required, user interaction needed, unchanged scope, and high impact on confidentiality but no impact on integrity or availability. No known exploits are currently reported in the wild, and no official patches are linked in the provided data, though fixed versions are known from Mbed TLS release notes. The vulnerability is classified under CWE-203 (Information Exposure Through Discrepancy).

For European organizations, the impact of this vulnerability is significant in scenarios where Mbed TLS is used within secure enclave environments or TEEs, especially in cloud infrastructure, IoT devices, or embedded systems that rely on RSA cryptography for secure communications or authentication. The ability to recover RSA private keys compromises the confidentiality of encrypted data, digital signatures, and authentication credentials, potentially leading to unauthorized data access, identity spoofing, and further lateral movement within networks. Organizations in sectors such as finance, telecommunications, critical infrastructure, and government services that deploy secure enclaves on potentially untrusted platforms are at heightened risk. The attack requires the adversary to have privileged access to the operating system layer beneath the enclave, which may be realistic in multi-tenant cloud environments or compromised host systems. Given the medium CVSS score and the complexity of the attack, the threat is moderate but could escalate if combined with other vulnerabilities or insider threats. The absence of known exploits in the wild suggests limited immediate risk, but the potential for key compromise warrants proactive mitigation, especially in high-value or sensitive deployments.

1. Upgrade Mbed TLS to version 2.28.2 or later, or 3.3.0 or later, where this vulnerability has been addressed. 2. If upgrading is not immediately feasible, increase the MBEDTLS_MPI_WINDOW_SIZE parameter to a value greater than 3, as larger window sizes mitigate the side-channel leakage exploited by this attack. 3. Restrict and monitor access to the operating system layer beneath secure enclaves to prevent untrusted OS-level adversaries from gaining the precise memory access information required for the attack. 4. Employ hardware and software side-channel protections such as constant-time cryptographic implementations and memory access pattern obfuscation within secure enclaves. 5. Conduct regular security audits and penetration testing focusing on enclave security and OS-level privilege boundaries. 6. For cloud environments, ensure tenant isolation and leverage cloud provider security features to minimize the risk of OS-level compromise. 7. Implement key rotation policies to limit the exposure window of any potentially compromised RSA keys. 8. Monitor cryptographic operation logs for anomalies that could indicate side-channel exploitation attempts.