CVE-2022-0778: DoS in OpenSSL Certificate Parsing

CVE-2022-0778 affects OpenSSL's BN_mod_sqrt() function, which computes modular square roots. The function contains a bug causing infinite loops when processing non-prime moduli. This occurs during parsing of certificates with compressed elliptic curves or explicit elliptic curve parameters with the base point encoded in compressed form. An attacker can craft certificates with invalid elliptic curve parameters to trigger the infinite loop and cause a denial of service.

The vulnerability scores CVSS 7.5 (HIGH). It was patched on March 15, 2022 in OpenSSL 3.0.2, 1.1.1n, and 1.0.2zd. Since certificate parsing occurs before signature verification, vulnerable systems include TLS clients, TLS servers, hosting providers, CAs, and any system parsing externally supplied certificates or private keys. A GitHub signal indicates sustained technical interest in this bug, with reference implementations comparing code before and after the patch.

System administrators and CISOs must urgently verify OpenSSL versions in production and apply available updates: OpenSSL 3.0.2 or later, 1.1.1n or later, or 1.0.2zd or later. Since the bug is exploitable through malformed certificates during parsing, it is critical to monitor logs from TLS services, certificate hosting systems, and CA systems for anomalies related to certificate parsing.