CVE-2025-26735 is a high-severity vulnerability classified under CWE-98, which pertains to improper control of filenames used in include or require statements within PHP programs. Specifically, this vulnerability affects the Grip theme developed by Candid themes, versions up to 1.0.9. The vulnerability allows for PHP Remote File Inclusion (RFI), a critical security flaw where an attacker can manipulate the filename parameter used in include or require statements to load malicious remote code. This occurs because the application does not properly validate or sanitize user input controlling the filename, enabling an attacker to specify an external URL or file path. Exploiting this vulnerability can lead to remote code execution, full system compromise, data theft, and disruption of service. The CVSS v3.1 base score is 7.5, indicating high severity, with the vector AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H. This means the attack can be performed remotely over the network, requires high attack complexity, no privileges, but some user interaction, and impacts confidentiality, integrity, and availability substantially. Although no known exploits are currently reported in the wild, the potential impact is significant due to the nature of RFI vulnerabilities. The vulnerability was published on May 19, 2025, and is recognized by CISA, indicating its importance in cybersecurity advisories. No patches or fixes have been linked yet, so affected users must be cautious and implement mitigations promptly.

For European organizations using the Grip theme by Candid themes, this vulnerability poses a serious risk. Many European businesses rely on PHP-based content management systems and themes for their websites and online services. Successful exploitation could lead to unauthorized remote code execution, allowing attackers to steal sensitive customer data, intellectual property, or disrupt business operations. The confidentiality, integrity, and availability of affected systems could be severely compromised, potentially leading to regulatory compliance violations under GDPR if personal data is exposed. Additionally, the high attack complexity and requirement for user interaction reduce but do not eliminate risk, as phishing or social engineering could facilitate exploitation. The lack of patches increases exposure time, making timely mitigation critical. This vulnerability could also be leveraged for lateral movement within corporate networks, increasing the scope of impact beyond the web server. European organizations in sectors such as finance, healthcare, e-commerce, and government are particularly at risk due to their reliance on secure web infrastructure and the sensitivity of their data.

Given the absence of official patches, European organizations should implement several specific mitigations: 1) Immediately audit all web applications using the Grip theme to identify affected versions and isolate vulnerable instances. 2) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious include/require parameter manipulations indicative of RFI attempts. 3) Disable allow_url_include and allow_url_fopen directives in PHP configurations to prevent remote file inclusion via URL. 4) Enforce strict input validation and sanitization on all user-supplied parameters, especially those controlling file paths. 5) Implement Content Security Policy (CSP) headers to restrict loading of external scripts and resources. 6) Monitor logs for unusual requests or errors related to file inclusion. 7) Educate users and administrators about phishing risks to reduce user interaction exploitation. 8) Consider temporarily disabling or replacing the Grip theme until a patch is released. 9) Stay updated with vendor advisories for patches or official fixes and apply them promptly once available.