CVE-2025-27587: 
OpenSSL vulnerability analysis and mitigation

OpenSSL 3.0.0 through 3.3.2 on the PowerPC architecture is vulnerable to a Minerva attack, discovered and reported in 2024. This disputed vulnerability (CVE-2025-27587) affects the EVP_DigestSign API implementation specifically on PowerPC systems (CVE Details, NVD).

The vulnerability exploits a timing side-channel in the P-364 curve implementation. Attackers can measure the time of signing random messages using the EVP_DigestSign API (Init, Update, and Final) to extract the K value (nonce) from signatures. By analyzing the bit size of the extracted nonce and comparing signing times between full-sized nonces and smaller nonces using statistical tests, attackers can determine a dependency between the bit size of K and the size of the side channel (GitHub Issue).

If successfully exploited, the vulnerability allows attackers to extract the private key from signatures. However, the timing signal is extremely small and requires the attacking process to run on the same physical system as the target, significantly limiting the practical impact (NVD).

The vulnerability specifically affects PowerPC architecture implementations. Users on other architectures are not impacted. For affected systems, no official mitigation has been published as the vulnerability is disputed and considered outside OpenSSL's threat model (GitHub Issue).