CVE-2026-77696

A flaw was found in OpenSSL. During SM2 signature generation, variable-time arithmetic operations are performed on secret values, creating an observable timing side-channel. An attacker capable of measuring signature generation times can collect timing data across multiple signing operations, which may allow them to recover the private key.

This issue is rated Moderate because SM2 signature generation can leak timing information about the secret nonce, which with many measurements may enable private-key recovery. Exploitation requires observing fine-grained signing times for SM2 operations and is not relevant when SM2 is unused.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

If SM2 is not required, disable or avoid SM2 signing in application configuration. Where SM2 must be used, restrict who can solicit large numbers of signatures.