CVE-2023-0216 is a high-severity vulnerability in OpenSSL version 3.0.0 involving an invalid pointer dereference during the processing of malformed PKCS7 data. Specifically, the vulnerability arises when an application invokes the functions d2i_PKCS7(), d2i_PKCS7_bio(), or d2i_PKCS7_fp() to decode PKCS7 structures. These functions do not properly handle malformed input, leading to a read of an invalid pointer. This results in an application crash, which can be exploited to cause a denial of service (DoS). Notably, the core OpenSSL TLS implementation does not call these functions, so the vulnerability primarily affects third-party applications that process untrusted PKCS7 data using these APIs. The vulnerability is classified under CWE-476 (NULL Pointer Dereference). The CVSS v3.1 base score is 7.5, reflecting a high severity due to the vulnerability’s network attack vector, low attack complexity, no privileges required, and no user interaction needed. The impact is limited to availability, as confidentiality and integrity are not affected. There are no known exploits in the wild at the time of publication, and no official patches have been linked yet. However, given the widespread use of OpenSSL in cryptographic operations and secure communications, any application that parses PKCS7 data using the vulnerable functions is at risk of crashing when processing crafted malicious input, potentially disrupting services or causing application downtime.

For European organizations, the impact of CVE-2023-0216 can be significant in environments where OpenSSL 3.0.0 is deployed and third-party applications handle PKCS7 data. This includes systems involved in secure email (S/MIME), digital signatures, certificate management, and other cryptographic workflows that utilize PKCS7 structures. An attacker could send specially crafted PKCS7 data to vulnerable applications, causing them to crash and resulting in denial of service. This could disrupt critical business operations, especially in sectors relying on secure communications such as finance, healthcare, government, and telecommunications. Although the vulnerability does not lead to data leakage or code execution, the availability impact can affect service reliability and trust. Organizations using custom or less common software that integrates OpenSSL PKCS7 parsing should carefully assess exposure. The lack of required authentication or user interaction means attacks could be launched remotely and automatically, increasing risk. The absence of known exploits currently reduces immediate threat but does not eliminate the risk of future exploitation.

European organizations should take the following specific mitigation steps: 1) Inventory all applications and services using OpenSSL 3.0.0, focusing on those that parse PKCS7 data with d2i_PKCS7(), d2i_PKCS7_bio(), or d2i_PKCS7_fp() functions. 2) Engage with software vendors or development teams to confirm whether these vulnerable functions are used and request patches or updates. 3) Where possible, apply input validation and sanitization on PKCS7 data before processing to detect and reject malformed inputs. 4) Implement network-level protections such as Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) to detect and block suspicious PKCS7 payloads or anomalous traffic patterns targeting these services. 5) Monitor application logs and crash reports for signs of exploitation attempts or unusual failures related to PKCS7 processing. 6) Consider deploying runtime application self-protection (RASP) or sandboxing techniques to contain crashes and prevent service-wide outages. 7) Maintain up-to-date backups and incident response plans to quickly recover from potential denial of service incidents. 8) Stay informed about OpenSSL updates and apply official patches promptly once available.