A timing and cache side-channel vulnerability exists in OpenSSL's SM2 private key operations on ARM64 and RISC-V platforms due to a non-constant-time scalar multiplication implementation. This flaw allows an attacker who can measure timing or cache access patterns during SM2 signing or decryption to potentially learn information about the secret scalar. The issue affects OpenSSL versions 4.0, 3.6, 3.5, and 3.4 on these architectures. Versions 3.0, 1.1.1, and 1.0.2 are not affected. Fixes are available in OpenSSL 4.0.3, 3.6.5, 3.5.9, and 3.4.8.