CVE-2025-43960 is a vulnerability found in Adminer version 4.8.1 that arises when the application uses the Monolog logging library. The issue is triggered by a crafted serialized payload containing an excessively large string length specifier (e.g., s:1000000000), which exploits PHP Object Injection mechanisms. This crafted payload causes the application to consume an excessive amount of memory, leading to a Denial of Service (DoS) condition. The vulnerability can be exploited remotely by unauthenticated attackers who send malicious serialized objects to the Adminer interface. The attack forces the server to allocate large amounts of memory, causing the Adminer interface to become unresponsive. Although the server may recover after several minutes, multiple concurrent exploit attempts can overwhelm the system, potentially causing a complete crash that requires manual intervention to restore service. The vulnerability leverages the interaction between Adminer’s deserialization process and Monolog’s logging, which does not properly validate or limit the size of serialized input. This flaw highlights the risks associated with unsafe deserialization and inadequate input validation in web applications that rely on PHP object serialization. No CVSS score has been assigned yet, and no known exploits are reported in the wild at the time of publication.

For European organizations, this vulnerability poses a significant risk to the availability of systems running Adminer 4.8.1 with Monolog logging enabled. Adminer is a popular database management tool used by developers and administrators to manage databases via a web interface. A successful exploitation could disrupt database management operations, potentially delaying critical business functions that rely on timely database access and maintenance. The DoS condition could affect internal IT infrastructure, web hosting environments, and cloud services that utilize Adminer, leading to operational downtime and increased recovery costs. Furthermore, the need for manual intervention to restore service after a crash could strain IT resources and increase incident response times. Although the vulnerability does not directly compromise confidentiality or integrity, the disruption of database management capabilities could indirectly impact data availability and business continuity. European organizations with regulatory requirements for uptime and service availability, such as those in finance, healthcare, and critical infrastructure sectors, may face compliance risks if this vulnerability is exploited.

To mitigate this vulnerability, organizations should first verify if their Adminer installations use Monolog for logging and identify if they are running version 4.8.1. Immediate steps include disabling or restricting access to Adminer interfaces from untrusted networks to reduce exposure to unauthenticated remote attacks. Implementing web application firewalls (WAFs) with rules to detect and block suspicious serialized payloads can help prevent exploitation attempts. Administrators should monitor server memory usage and set resource limits to prevent excessive memory consumption by PHP processes. Applying input validation and sanitization on serialized data before deserialization is critical; if possible, replace unsafe deserialization with safer alternatives or use libraries that enforce strict type and size checks. Organizations should track vendor advisories for patches or updates addressing this issue and apply them promptly once available. Additionally, logging and alerting on anomalous requests containing large serialized strings can aid in early detection of exploitation attempts. Regular backups and incident response plans should be updated to handle potential DoS incidents caused by this vulnerability.