Format String Vulnerability in OpenSSL CMP Client

CVE-2026-63073

What is CVE-2026-63073?

The OpenSSL CMP client has a flaw in its message validation process where peer-supplied sender distinguished names can be improperly passed as format strings. This occurs in scenarios where the client expects a specific sender or uses a pinned server certificate. If an attacker intercepts or injects a malicious CMP response, the client may experience a crash due to malicious format strings leading to a denial of service. This vulnerability does not allow for unauthorized memory access or code execution, but it effectively disrupts the service operations of the affected client.

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