CVE-2026-106431 MongoDB CVE debrief

Who should care

Defenders responsible for MongoDB C Driver deployments should assess exposure and verify versions to prevent potential memory corruption or process termination. This includes reviewing application code for BSON bulk-writer API usage and precise cumulative document size handling, and monitoring for potential issues. Operators, platform administrators, vulnerability management teams, and security teams should be aware of the vulnerability and its potential

Why it matters

CVE-2026-106431 is a medium-severity vulnerability in the MongoDB C Driver's BSON bulk document writer. Defenders should prioritize verifying and updating driver versions, reviewing application code, and monitoring for potential issues to prevent memory corruption or process termination.

• Potential memory corruption or process termination
• Need to verify and update MongoDB C Driver versions
• Review application code for BSON bulk-writer API usage
• Monitor for potential issues with precise cumulative document size handling

Technical summary

The MongoDB C Driver's BSON bulk document writer has an off-by-one error that can cause a one-byte heap buffer overflow when a document ends at a specific buffer boundary. This requires the application to use the BSON bulk-writer API and produce a precise cumulative document size. The vulnerability has a medium severity and a 5.9 CVSS score. An actor who can influence document sizes can corrupt adjacent process memory or terminate the process. Defenders should prioritize verifying and updating MongoDB C Driver versions to prevent potential memory corruption or process termination.

Defensive priority

Defenders should prioritize verifying and updating MongoDB C Driver versions to prevent potential memory corruption or process termination.

Recommended defensive actions

• Verify MongoDB C Driver versions and update to 1.30.13 or later for versions 0.5.0, or 2.5.6 or later for versions 2.0.0
• Review application code for use of the BSON bulk-writer API and precise cumulative document size handling
• Monitor for potential memory corruption or process termination issues
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE Program and NVD records provide details on the vulnerability, including its description, CVSS score, and affected versions. The MongoDB C Driver's BSON bulk document writer has an off-by-one error that can cause a one-byte heap buffer overflow. This issue requires the application to use the BSON bulk-writer API and produce a precise cumulative document size. Defenders should verify and update MongoDB C Driver versions to prevent potential memory corruption or process termination. The vulnerability has a medium severity and a 5

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.