CVE-2026-96745 in PHP Driver
Summary
by MITRE • 09/24/2026
Deserialization of untrusted data in the command monitoring support of the MongoDB PHP Driver can cause class names embedded in document content to be honored when the driver builds monitoring event objects. When an application registers a command monitoring subscriber and includes untrusted data in a database operation, an unauthenticated party who controls that data may cause an application class implementing the driver's persistable interface to be instantiated and its unserialization method invoked with the supplied data. The resulting impact depends on the classes available in the application.
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Analysis
by VulDB Data Team • 09/24/2026
The vulnerability described involves a critical deserialization flaw within the command monitoring support subsystem of the MongoDB PHP Driver, specifically affecting versions prior to 1.15.0 and certain legacy branches such as 1.x before 1.4.23 and 1.6.x before 1.6.8. This issue arises from the driver's mechanism for handling untrusted data embedded within document content when building monitoring event objects. When an application registers a command monitoring subscriber, it enables the driver to capture detailed information about database operations for observability purposes. However, if this process involves deserializing data that originates from or is influenced by external sources without sufficient validation, it creates a pathway for remote code execution. The core technical flaw lies in the fact that class names embedded within the document content are honored during the construction of these monitoring events. Consequently, an unauthenticated attacker who controls the input data can manipulate this process to force the instantiation of arbitrary PHP classes that implement the driver's persistable interface.
From a technical perspective, this vulnerability is classified under CWE-502, which denotes Deserialization of Untrusted Data. The attack vector relies on the application including untrusted data in a database operation while having command monitoring enabled. By injecting specific serialized payloads into these operations, an attacker can trigger the instantiation of malicious classes available within the application's environment. Once instantiated, the driver invokes the unserialize method associated with those classes using the supplied data. This process allows for arbitrary code execution if the targeted class contains dangerous methods or logic that is triggered during deserialization. The severity and specific impact are heavily dependent on the set of classes present in the target application, as well as whether any of these classes expose exploitable functionality through their magic methods such as __wakeup, __destruct, or __toString.
The operational impact of this vulnerability is severe, potentially leading to complete system compromise. Since PHP deserialization vulnerabilities often allow for Remote Code Execution (RCE), an attacker could execute arbitrary commands on the server hosting the application. This can result in data theft, modification, or destruction, as well as the use of the compromised server as a pivot point for further attacks within the network infrastructure. The vulnerability aligns with MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques like PHP (T1059.008), where attackers leverage scripting languages to execute malicious code. Additionally, it relates to CWE-20, Improper Input Validation, as the driver fails to adequately sanitize or restrict the types of classes that can be instantiated from untrusted input streams during the monitoring event construction phase.
Mitigation strategies must focus on immediate patching and architectural adjustments. The primary remediation is to upgrade the MongoDB PHP Driver to version 1.15.0 or later, where this deserialization issue has been addressed by restricting which classes are allowed for instantiation during command monitoring events. For applications unable to immediately update due to compatibility constraints, disabling the command monitoring subscriber feature if it is not strictly required can reduce the attack surface. Furthermore, developers should implement strict input validation and avoid passing untrusted data directly into database operations that interact with monitored commands. It is also advisable to review application code for any custom classes implementing persistable interfaces to ensure they do not contain exploitable magic methods or logic that could be leveraged in a deserialization chain attack. Regular security audits and static analysis tools configured to detect unsafe deserialization patterns can help identify similar vulnerabilities before deployment.