CVE-2025-9565 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Blocksy Companion plugin for WordPress, specifically affecting the blocksy_newsletter_subscribe shortcode. This vulnerability exists in all versions up to and including 2.1.10 due to improper neutralization of input during web page generation, classified under CWE-79. The root cause is insufficient input sanitization and output escaping of user-supplied attributes, which allows an authenticated attacker with contributor-level access or higher to inject arbitrary malicious scripts into pages. These scripts execute in the context of any user who views the compromised page, potentially leading to session hijacking, privilege escalation, or unauthorized actions on behalf of the victim user. The vulnerability does not require user interaction beyond visiting the injected page and does not require administrator privileges, only contributor-level access, which is a relatively low threshold in WordPress environments. The CVSS v3.1 base score is 6.4 (medium severity), reflecting network attack vector, low attack complexity, privileges required (low), no user interaction, and a scope change with partial impact on confidentiality and integrity but no impact on availability. No known exploits are currently reported in the wild, and no official patches have been linked yet. The vulnerability was published on September 17, 2025, and assigned by Wordfence.

For European organizations using WordPress websites with the Blocksy Companion plugin, this vulnerability poses a significant risk. Stored XSS can lead to theft of user credentials, session tokens, or other sensitive information, enabling attackers to impersonate users or escalate privileges. This is particularly critical for organizations handling personal data under GDPR, as exploitation could result in data breaches and regulatory penalties. Contributor-level access is often granted to content creators or editors, making insider threats or compromised accounts a realistic attack vector. The injected scripts could also be used to deliver malware or redirect users to phishing sites, damaging organizational reputation and trust. Since WordPress powers a large portion of European websites, including e-commerce, government, and media sites, the potential impact spans confidentiality and integrity of data and user trust. The lack of known exploits in the wild suggests a window for proactive mitigation before widespread exploitation occurs.

Organizations should immediately audit their WordPress installations to identify the presence and version of the Blocksy Companion plugin. Until an official patch is released, the following specific mitigations are recommended: 1) Restrict contributor-level permissions strictly to trusted users and review user roles to minimize unnecessary privileges. 2) Implement Web Application Firewall (WAF) rules to detect and block suspicious payloads targeting the blocksy_newsletter_subscribe shortcode parameters. 3) Employ Content Security Policy (CSP) headers to restrict script execution sources, reducing the impact of injected scripts. 4) Conduct regular security scans focusing on stored XSS indicators within WordPress content. 5) Monitor logs for unusual activity from contributor accounts. 6) Educate content contributors about the risks of uploading untrusted content or scripts. Once a patch is available, prioritize immediate update of the plugin to the fixed version. Additionally, consider isolating critical WordPress instances and backing up data regularly to enable quick recovery.