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PatchSiren cyber security CVE debrief

CVE-2026-9740 MongoDB CVE debrief

A vulnerability in MongoDB Server's BSON validation logic allows an unauthenticated user to crash the mongod process by sending a specially crafted message. The BSON validator's handling of certain nested binary data structures permits uncontrolled mutual recursion between validation functions, where each re-entry resets internal depth tracking.

Vendor
MongoDB
Product
MongoDB Server
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-15
Advisory published
2026-06-09
Advisory updated
2026-06-15

Who should care

Users of MongoDB Server are advised to take action.

Technical summary

The vulnerability has a CVSS score of 8.7 and is classified as HIGH severity. It was published on [cvePublishedAt] and last modified on [cveModifiedAt].

Defensive priority

HIGH

Recommended defensive actions

  • Apply the patch or update to the latest version of MongoDB Server.
  • Restrict access to the MongoDB Server to only trusted users.

Evidence notes

The CVE record was obtained from the official CVE website [resourceLinkAnnotations:cve-org]. Additional information was obtained from the NVD detail page [resourceLinkAnnotations:nvd].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-9740 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-9740

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-9740 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-9740

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental 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.