CVE-2025-43960 in Adminer
Summary
by MITRE • 08/25/2025
Adminer 4.8.1, when using Monolog for logging, allows a Denial of Service (memory consumption) via a crafted serialized payload (e.g., using s:1000000000), leading to a PHP Object Injection issue. Remote, unauthenticated attackers can trigger this by sending a malicious serialized object, which forces excessive memory usage, rendering Adminer’s interface unresponsive and causing a server-level DoS. While the server may recover after several minutes, multiple simultaneous requests can cause a complete crash requiring manual intervention.
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Analysis
by VulDB Data Team • 09/13/2025
CVE-2025-43960 represents a critical denial of service vulnerability affecting Adminer 4.8.1 when integrated with Monolog logging functionality. This vulnerability stems from improper handling of serialized data structures within the application's logging mechanism, creating a dangerous condition where malicious input can trigger excessive memory consumption. The flaw manifests when Adminer processes a crafted serialized payload containing a string with an extremely large length specification such as s:1000000000, which instructs PHP to allocate massive amounts of memory during deserialization. This vulnerability maps directly to CWE-400, which categorizes improper handling of untrusted input leading to resource exhaustion, and aligns with ATT&CK technique T1499.100, specifically targeting resource consumption via malicious input manipulation.
The technical exploitation of this vulnerability occurs through PHP object injection mechanisms that leverage the unserialize() function within the Monolog logging component. When Adminer receives a malicious serialized object, the logging system attempts to deserialize the payload without proper validation or length restrictions, causing PHP to allocate memory proportional to the specified string length. This process continues until system resources are exhausted, resulting in memory exhaustion that renders the entire Adminer interface unresponsive. The vulnerability is particularly dangerous because it operates at the PHP level, where memory allocation is not limited by typical application boundaries, allowing attackers to consume system resources far beyond normal operational limits.
Remote attackers can exploit this vulnerability without authentication requirements, making it especially concerning for publicly accessible Adminer installations. The attack vector involves sending a single malicious request containing the oversized serialized payload, which causes immediate memory consumption spikes that can overwhelm even moderately sized servers. Multiple simultaneous requests compound the issue, potentially causing complete system crashes that require manual intervention and server restarts. The recovery time can extend to several minutes, during which the application remains unavailable to legitimate users, creating significant operational impact for database administrators who rely on Adminer for their daily tasks.
Mitigation strategies for this vulnerability should focus on input validation and resource limiting measures. Administrators should immediately upgrade to Adminer versions that address this specific issue, as the vulnerability has been identified and patched in subsequent releases. Implementing proper serialization validation within the logging component can prevent malicious payloads from being processed, while PHP configuration settings such as memory_limit and max_execution_time can provide additional protection layers. Network-level protections including rate limiting and input filtering can also reduce the impact of such attacks, though the most effective solution remains the application-level fix that prevents deserialization of untrusted input entirely. Organizations should also implement monitoring systems to detect unusual memory consumption patterns that could indicate exploitation attempts.