CVE-2025-54869 is a Denial of Service (DoS) vulnerability affecting the Setasign FPDI PHP library, versions 2.6.2 and below. FPDI is widely used to read pages from existing PDF documents and reuse them as templates within the FPDF framework, commonly employed in web applications for PDF manipulation. The vulnerability arises due to improper resource allocation controls (CWE-770), where the library does not impose limits or throttling on memory usage when processing user-supplied PDF files. An attacker can exploit this by uploading a crafted malicious PDF file that triggers excessive memory consumption during processing, causing the server-side PHP script to crash or become unresponsive. This leads to service disruption and potential sustained unavailability if repeated attacks occur. The vulnerability requires low privileges (limited privileges) and no user interaction, with network attack vector, making it relatively easy to exploit remotely. The issue has been addressed in FPDI version 2.6.3, which implements proper resource management to prevent memory exhaustion. No known exploits are currently reported in the wild, but the medium CVSS 4.0 score of 6.0 reflects the moderate risk posed by this vulnerability, primarily impacting availability without compromising confidentiality or integrity.

For European organizations, especially those relying on PHP-based web applications that utilize FPDI for PDF processing (e.g., document management systems, invoicing platforms, or content management systems), this vulnerability poses a risk of service disruption. Attackers could cause denial of service by sending malicious PDFs, leading to downtime, degraded user experience, and potential loss of business continuity. Organizations handling high volumes of PDF uploads or automated PDF processing are particularly vulnerable. The impact is more pronounced for public-facing services where attackers can easily submit malicious files. While confidentiality and integrity are not directly affected, the availability impact can disrupt critical workflows, compliance reporting, or customer-facing portals. This could indirectly affect regulatory compliance under GDPR if service unavailability impacts data subject rights or service commitments.

1. Immediate upgrade of FPDI to version 2.6.3 or later to ensure the vulnerability is patched. 2. Implement strict input validation and file type verification to restrict PDF uploads to trusted sources and scan files for anomalies before processing. 3. Employ resource limits at the PHP runtime level, such as memory_limit and max_execution_time, to prevent excessive resource consumption from any single request. 4. Use sandboxing or isolated processing environments (e.g., containerization) for PDF processing to contain potential crashes and prevent impact on the entire application. 5. Monitor application logs and resource usage patterns to detect unusual spikes indicative of exploitation attempts. 6. Consider implementing rate limiting or CAPTCHA challenges on PDF upload endpoints to mitigate automated attack attempts. 7. Regularly review and update third-party dependencies to minimize exposure to known vulnerabilities.