CVE-2026-82054 in Server
Summary
by MITRE • 09/08/2026
A security issue exists in MongoDB server's JSON Pointer parser used during $jsonSchema query filter processing. When a find command includes a specially crafted $jsonSchema filter field, the parser processes the input without enforcing adequate limits on iteration count or total allocation size, resulting in significant memory amplification. Under concurrent request load, the cumulative memory consumption can exhaust available heap memory, causing the server's out-of-memory handler to terminate the mongod process and deny service to all connected clients.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability identified involves a critical flaw within the MongoDB server’s JSON Pointer parser, specifically during the processing of $jsonSchema query filters. This component is responsible for interpreting schema validation rules applied to documents retrieved via find commands. The core technical deficiency lies in the lack of adequate constraints on iteration counts and total memory allocation sizes when parsing these schemas. When a client submits a specially crafted $jsonSchema filter field, the parser enters an unbounded processing loop or allocates excessive amounts of heap memory without verifying that the input size is reasonable relative to system resources. This design oversight allows for significant memory amplification, where a relatively small malicious payload can trigger disproportionately large resource consumption on the server side.
The operational impact of this flaw is severe, primarily manifesting as a denial-of-service condition against MongoDB instances under concurrent load conditions. As multiple clients simultaneously submit these crafted requests, the cumulative effect rapidly exhausts the available heap memory allocated to the mongod process. Once the memory limit is breached, the database server triggers its out-of-memory handler, which results in the immediate termination of the mongod process. This abrupt shutdown disrupts all active connections and halts any ongoing transactions or queries, effectively rendering the service unavailable to legitimate users until the instance is manually restarted or automatically recovered by an external orchestration system.
From a classification perspective, this vulnerability aligns with CWE-400, which describes uncontrolled resource consumption leading to denial of service. The attack vector leverages the server’s own parsing logic against itself, exploiting the trust placed in input validation mechanisms during schema processing. In terms of adversarial tactics, this behavior corresponds to ATT&CK technique T1498, specifically Network Denial of Service via Resource Exhaustion, as it aims to degrade service availability by consuming critical system resources rather than compromising data integrity or confidentiality directly.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Administrators should apply the latest security patches provided by MongoDB that address this specific parsing flaw in the $jsonSchema handler. In environments where patching is not immediately feasible, implementing strict rate limiting and request size restrictions at the network or application gateway level can help mitigate the impact of such attacks. Additionally, configuring appropriate memory limits for the mongod process using operating system controls like cgroups on Linux systems can prevent a single instance from consuming all available host memory, thereby protecting other critical services running on the same infrastructure. Regular auditing of schema definitions and ensuring that complex nested structures are validated against reasonable depth and size constraints before reaching the parser is also recommended to reduce exposure to similar vulnerabilities in future updates.