CVE-2026-106429 MongoDB CVE debrief

Who should care

Defenders responsible for MongoDB deployments using libmongocrypt should assess their exposure and verify the integrity of KMS endpoints. Additionally, developers using libmongocrypt in their applications should ensure that they are using a version that includes the fix.

Why it matters

Defenders should care about this vulnerability because it can cause application process termination, potentially impacting data availability. They should verify the integrity of KMS endpoints and ensure that applications using libmongocrypt are updated to a version that includes the fix.

• Potential application process termination due to allocation failure
• Need to verify integrity of KMS endpoints
• Requirement to update applications using libmongocrypt to a fixed version
• Possible impact on data availability due to denial-of-service

Technical summary

The vulnerability exists due to an integer underflow in the KMS endpoint-parsing logic of MongoDB libmongocrypt. This can cause an allocation failure that terminates the application process when an authenticated user modifies a key document in the key vault collection or when an application accepts a KMS endpoint containing a colon after its path or query during key creation. The issue can be triggered by a malformed KMS endpoint, potentially impacting data availability. Defenders should prioritize verifying the integrity of KMS endpoints and ensuring that applications using libmongocrypt are updated to a version that includes the fix.

Defensive priority

Defenders should prioritize verifying the integrity of KMS endpoints and ensuring that applications using libmongocrypt are updated to a version that includes the fix.

Recommended defensive actions

• Verify the integrity of KMS endpoints
• Ensure applications using libmongocrypt are updated to a version that includes the fix
• Monitor for suspicious activity related to KMS endpoint modifications
• 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 about the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not provide information on exploitation or specific attack vectors.

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.