CVE-2025-63058 is a security vulnerability identified in the Hiroaki Miyashita Custom Field Template plugin, specifically affecting versions up to and including 2.7.4. The vulnerability allows an unauthorized control sphere—meaning an attacker without proper authorization—to retrieve embedded sensitive system information from the affected plugin. This type of exposure typically involves leakage of configuration details, environment variables, or other confidential data embedded within the plugin's custom fields, which can be leveraged to facilitate further attacks such as privilege escalation, lateral movement, or targeted exploitation. The vulnerability was reserved in late October 2025 and published in December 2025, but no CVSS score has been assigned yet, and no known exploits have been reported in the wild. The lack of a CVSS score suggests that the vulnerability is newly disclosed and may not yet be fully analyzed. The plugin is commonly used in web content management systems to extend custom field functionality, making it a potential target for attackers seeking to gain insight into system internals. Since the vulnerability allows unauthorized data retrieval, it implies that authentication or proper authorization checks are either missing or insufficient. This increases the attack surface significantly, especially for publicly accessible web environments. The absence of patch links indicates that a fix may not yet be available, requiring organizations to implement interim mitigations.

For European organizations, the exposure of sensitive system information can have serious consequences. Confidential data leakage can lead to the compromise of internal systems, intellectual property theft, and facilitation of advanced persistent threats. Attackers gaining system details can craft more effective attacks, including privilege escalation or exploitation of other vulnerabilities. Organizations in sectors with strict data protection regulations, such as finance, healthcare, and government, face increased compliance risks and potential fines under GDPR if sensitive data is exposed. The vulnerability could also undermine trust in affected services and damage reputations. Since the plugin is used in web environments, availability may not be directly impacted, but integrity and confidentiality are at risk. The lack of known exploits suggests a window of opportunity for defenders to act before widespread attacks occur. However, the ease of exploitation without authentication raises the threat level significantly.

Until an official patch is released, European organizations should take proactive steps to mitigate risk. First, conduct an inventory to identify all instances of the Hiroaki Miyashita Custom Field Template plugin in use, especially versions up to 2.7.4. Restrict access to affected web applications by implementing strict network segmentation and access controls, limiting exposure to trusted users only. Employ web application firewalls (WAFs) with custom rules to detect and block suspicious requests targeting the plugin's endpoints. Monitor logs for unusual access patterns or attempts to retrieve sensitive data. If feasible, disable or remove the plugin temporarily to eliminate the attack vector. Engage with the vendor or community to obtain patches or updates as soon as they become available. Additionally, conduct security awareness training for administrators to recognize and respond to potential exploitation attempts. Implement regular vulnerability scanning and penetration testing focused on web applications to detect similar issues proactively.