CVE-2026-114647 MongoDB CVE debrief

Who should care

Developers and administrators using MongoDB C# Driver in their applications should assess and verify their usage of FindOneAndReplace operations to prevent potential data integrity issues. This includes reviewing and validating the operations to ensure they are not vulnerable to unintended update operator application. Additionally, security teams and operators should be aware of the potential risks and take necessary precautions to mitigate them.

Why it matters

CVE-2026-114647 is a vulnerability in the MongoDB C# Driver that allows unintended update operators to be applied when replacing documents with user-supplied field names starting with a dollar sign. Developers and administrators using MongoDB C# Driver should assess and verify their usage of FindOneAndReplace operations to prevent potential data integrity issues.

• Potential unintended data modification due to update operator application
• Need to verify and validate FindOneAndReplace operations
• Possible data integrity issues if not properly addressed

Technical summary

The MongoDB C# Driver does not reject replacement documents with top-level field names starting with a dollar sign in FindOneAndReplace operations, potentially allowing unintended update operators to be applied. This issue can lead to potential data integrity problems if not addressed. The vulnerability affects MongoDB C# Driver and can be mitigated by assessing and verifying FindOneAndReplace operations. The CVE record was published on 2026-10-22T19:17:38.437Z and has not been modified since then. The effect is limited to the document matched by the application's own filter.

Defensive priority

Assess and verify MongoDB C# Driver usage, review FindOneAndReplace operations

Recommended defensive actions

• Review and verify MongoDB C# Driver version usage in your application
• Assess FindOneAndReplace operations for potential unintended update operator application
• Update to a fixed version of MongoDB C# Driver if available
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The MongoDB C# Driver vulnerability allows unintended update operators to be applied when replacing documents with user-supplied field names starting with a dollar sign. This issue is based on the CVE Program and NIST NVD records. The effect is limited to the document matched by the application's own filter, whose contents can be modified in ways the application did not intend. Evidence is limited to public CVE and NVD records.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.