Description

An issue in MongoDB Server's aggregation framework could allow an authenticated user to trigger an out-of-bounds memory read by providing a specially formed numeric parameter in a certain aggregation pipeline stage. This could result in a server crash (denial of service) and may potentially expose a limited amount of memory contents.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-08-11T19:17:22.620Z",
  "pubdate": "2026-08-11T19:17:22.620Z",
  "executiveSummary": "An out-of-bounds memory read vulnerability has been identified within the aggregation framework of MongoDB Server. This security flaw enables an authenticated adversary to trigger an out-of-bounds memory read operation by supplying a specifically crafted numeric parameter targeting a precise aggregation pipeline stage. The primary technical impact of successful exploitation includes a complete server crash resulting in a denial of service, alongside the potential exposure of sensitive data residing within adjacent memory structures.\nThe affected system is MongoDB Server. Risk implications are moderate to high, as the vulnerability threatens service availability and confidentiality by potentially leaking limited amounts of memory contents. Attacker capabilities require authenticated access to the database environment, meaning the threat actor must already possess valid credentials to interact with the target instance and execute aggregation queries.\nExploitation requirements dictate that the authenticated user must construct and submit a malicious payload leveraging the vulnerable aggregation pipeline stage with malformed numeric parameters. There are no mentions of remote code execution, but the capability to repeatedly crash the database daemon introduces significant operational risks and availability concerns for enterprise deployments relying on continuous database uptime.",
  "technicalDetails": "The root cause of the vulnerability stems from improper bounds checking or validation logic within the MongoDB Server aggregation framework when processing numeric parameters inside a specific aggregation pipeline stage. When the vulnerable component parses the maliciously crafted numeric input, it fails to verify whether the specified value aligns with the actual allocated buffer boundaries, resulting in an out-of-bounds memory read.\nThe vulnerable component is the aggregation pipeline processing engine within MongoDB Server. The attack flow begins when an authenticated user connects to the database instance and issues an aggregation query containing the specially formed numeric parameter within the targeted pipeline stage. Upon parsing the malicious parameter, the aggregation engine attempts to read memory past the designated buffer boundary.\nAuthentication and privilege requirements specify that the attacker must be an authenticated user. Network exposure depends on the database deployment configuration, though MongoDB instances exposed to untrusted networks or multi-tenant environments face elevated exposure levels. The payload behavior involves delivering the malformed numeric argument to the vulnerable aggregation stage, which causes the memory management subsystem to access invalid or unintended memory addresses.\nThe post-exploitation impact bifurcates into two main consequences: availability degradation and information disclosure. First, accessing unmapped or protected memory addresses typically triggers an access violation or segmentation fault, causing the database server process to terminate abruptly, thereby achieving a denial of service. Second, if the read operation successfully accesses valid memory regions outside the intended buffer, the contents of those memory addresses may be inadvertently exposed, potentially leaking sensitive information such as cached database queries, internal state data, or remnants of other user sessions depending on memory layout and heap structure."
}