CVE-2026-54875

/// Technical description

Issue summary: A non-constant-time optimized implementation of scalar

point multiplication is used for SM2 private key operations on ARM64 and

RISC-V platforms.

Impact summary: An attacker able to measure the time taken by, or to observe

the cache-line access pattern of SM2 signing or decryption on an affected

platform can learn information about the secret scalar.

CWE: CWE-208: Observable Timing Discrepancy

Description: On ARM64 and RISC-V processors, the SM2 curve uses an optimized

scalar multiplication implementation whose conditional branches and table

look ups are chosen according to the bits of the secret scalar. The execution

time and the cache-access pattern therefore depend on the long-term private

key (during SM2 decryption) or the per-signature nonce (during SM2 signature

generation), forming a timing and cache side-channel.

FIPS Impact: no

SM2 is not a FIPS algorithm and the optimized SM2 implementation is not part

of the FIPS module.

OpenSSL 4.0, 3.6, 3.5 and 3.4 are

/// Remediation

Check the references section for vendor advisories and patches from openssl. Update openssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// Affected products

/// References