CVE-2026-96749 MongoDB CVE debrief

Who should care

Defenders responsible for maintaining and securing applications that use the MongoDB Python Driver should assess exposure and prioritize patching. This includes operators, security teams, and vulnerability management teams who need to verify the MongoDB Python Driver version and apply patches to prevent potential crashes or other impacts.

Why it matters

Defenders should prioritize verifying the MongoDB Python Driver version and applying patches to prevent potential crashes or other impacts. This vulnerability may allow an attacker to cause a write outside the bounds of an allocated buffer, potentially leading to a crash or other unspecified impact. Affected applications and systems should be identified and patched as soon as possible.

• Potential application crashes or instability
• Possible data corruption or loss
• Required verification of MongoDB Python Driver version and patching
• Potential for denial-of-service (DoS) attacks

Technical summary

The MongoDB Python Driver's native extension is vulnerable to an integer overflow in the BSON document encoding component, which may cause a write outside the bounds of an allocated buffer. This vulnerability may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party with no privileges who can place a very large value into data that an application encodes may, depending on how the native extension was built, cause a write outside the bounds of an allocated buffer inside the application's own.

Defensive priority

Defenders should prioritize verifying the MongoDB Python Driver version and applying patches to prevent potential crashes or other impacts.

Recommended defensive actions

• Verify the MongoDB Python Driver version and apply patches
• Review application code for potential workarounds or mitigations
• Monitor for potential crashes or other impacts
• 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 vulnerability is caused by an integer overflow in the BSON document encoding component, which may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. The MongoDB Python Driver's native extension is vulnerable to this issue, and defenders should verify the driver version and apply patches to prevent potential crashes.

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.