CVE-2026-114651 MongoDB CVE debrief

Who should care

Defenders and developers using the MongoDB C# Driver should assess exposure and prioritize verification of the patched version. They should review application logs for unusual data access patterns and implement additional security measures to restrict data access and prevent unauthorized data supply to the application. Security teams should verify the patched version and monitor for potential data exposure.

Why it matters

CVE-2026-114651 is a medium-severity vulnerability in the MongoDB C# Driver that can cause data left over from previously processed content to be returned when specially crafted serialized input is parsed. Defenders should prioritize verifying the patched version and monitoring for unusual data access patterns.

• Data exposure and potential unauthorized access to sensitive information.
• Residual data from unrelated requests or principals may be surfaced as legitimate values.
• Verification of patched version and monitoring for unusual data access patterns are necessary.

Technical summary

The vulnerability is caused by a memory-handling weakness in the BSON deserialization component of the MongoDB C# Driver. When specially crafted serialized input is parsed, data left over from previously processed content may be returned. This can result in disclosure of a limited amount of information belonging to other requests or principals of the consuming application. The weakness may cause data left over from previously processed content to be returned when specially crafted serialized input is parsed, allowing an unauthenticated party to surface residual bytes from unrelated data processed earlier on the same execution thread as legitimate values.

Defensive priority

Defenders should prioritize verifying the patched version of the MongoDB C# Driver and monitoring for unusual data access patterns.

Recommended defensive actions

• Verify the version of the MongoDB C# Driver and upgrade to 3.13.0 or later if currently using a vulnerable version.
• Monitor application logs for unusual data access patterns or residual data exposure.
• Implement additional security measures to restrict data access and prevent unauthorized data supply to the application.
• 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.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source item provide details on the vulnerability, but limited information is available on exploitation or victim impact. Defenders should verify the patched version of the MongoDB C# Driver and review application logs for unusual data access patterns. The vulnerability is caused by a memory-handling weakness in the BSON deserialization component, and residual bytes from unrelated data processed earlier on the same execution thread may be surfaced as legitimate values.

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.