CVE-2026-18708 in MongoDB
Summary
by MITRE • 08/11/2026
An issue in MongoDB Server's JavaScript scripting engine could allow an authenticated user with write privileges to cause code they control to be executed within the query scope of other users, through a specially crafted stored value processed during an internal maintenance cycle. This could result in corruption of query results affecting other users and denial of service targeted at their operations on the same database. Impact is limited to the scripting engine's execution sandbox, which does not provide access to database, filesystem, or network resources.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability resides within MongoDB Server's JavaScript scripting engine, representing a sophisticated privilege escalation and code injection flaw that leverages authenticated write permissions to compromise query integrity across multiple user contexts. The technical mechanism involves a specially crafted stored value that gets processed during internal maintenance cycles, creating a vector where malicious code can be executed within the query scope of other users who subsequently access that data. The vulnerability operates through MongoDB's JavaScript engine sandbox, which while designed to provide isolation, contains implementation flaws that allow code execution in contexts beyond what should be permitted. According to CWE-94, this represents a weakness in the scripting engine's input validation and execution context management, where untrusted data processing during maintenance operations creates an attack surface for arbitrary code execution. The ATT&CK framework categorizes this under T1059.007 for JavaScript execution within database environments, highlighting the sophisticated nature of database-based command and control capabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass data integrity corruption and service disruption across shared database environments. When an authenticated user with write privileges crafts malicious stored values, these inputs can be executed during maintenance operations that affect all users querying the same database. This creates a scenario where one user's malicious input can corrupt query results for multiple other users simultaneously, leading to cascading failures in database operations and potentially complete denial of service conditions. The vulnerability's scope is particularly concerning in multi-tenant database environments where isolation between different user groups is expected but compromised through this scripting engine flaw. The execution sandbox limitation prevents direct access to underlying system resources, yet the indirect impact on query results and operational continuity can still result in significant business disruption.
Mitigation strategies must address both the immediate vulnerability exploitation and the underlying architectural issues within MongoDB's JavaScript processing mechanisms. Organizations should implement strict input validation for all stored values that may be processed during maintenance cycles, ensuring that no user-controllable data can influence script execution contexts. The recommended approach involves disabling or restricting JavaScript execution in database environments where such privilege escalation vectors exist, particularly in multi-user scenarios where different security contexts must be maintained. Database administrators should also monitor and audit write operations that could potentially introduce malicious stored values, implementing automated scanning tools to detect suspicious input patterns before they can be processed during maintenance cycles. Additionally, organizations should consider implementing network segmentation and access controls to limit the scope of potential exploitation while maintaining essential database functionality.
The vulnerability demonstrates how seemingly isolated components within database systems can create unexpected attack vectors when integrated into broader processing workflows. The intersection of JavaScript engine capabilities with internal maintenance operations creates a complex security landscape where traditional database isolation principles may be bypassed through carefully crafted data inputs. This type of vulnerability particularly affects MongoDB deployments in environments where JavaScript is enabled for database operations, highlighting the importance of understanding how scripting engines interact with database maintenance processes. Security teams must recognize that vulnerabilities like this can exist even in well-established systems when complex interactions between different functional components are not properly secured against cross-context execution scenarios. The remediation approach should focus on eliminating the specific exploitation path while maintaining necessary database functionality through proper privilege management and input sanitization procedures.
This vulnerability type represents a class of issues where database scripting capabilities become attack surfaces for indirect code execution, requiring careful consideration of how user-controllable data flows through system maintenance operations. The technical implementation flaw lies in MongoDB's handling of stored JavaScript values during internal processing cycles, where the security boundaries between different user contexts are not properly enforced. Organizations implementing database security measures should consider this vulnerability as part of broader database hardening strategies that address JavaScript engine security, input validation, and privilege management controls. The impact on system availability and data integrity makes this a critical concern for database administrators who must balance operational requirements with security considerations in their MongoDB deployments.