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CVE-2026-9743 MongoDB CVE debrief

CVE-2026-9743 is a HIGH severity vulnerability in MongoDB Server 8.0. An aggregation stage can leave its _subPipeline field null during processing of certain pipelines. If a getMore is subsequently issued on the same cursor, the server may dereference this null sub-pipeline when reattaching to the operation context, accessing an invalid address and crashing the process. This issue allows an authenticated user who can run aggregation pipelines to cause a denial of service by issuing a specially crafted aggregation followed by getMore on affected versions.

Vendor
MongoDB
Product
MongoDB server
CVSS
HIGH 7.1
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 8.0 who have authenticated users with the ability to run aggregation pipelines.

Technical summary

The vulnerability exists in the aggregation stage of MongoDB Server 8.0. A specially crafted aggregation pipeline can leave the _subPipeline field null. Subsequent getMore operations on the same cursor can cause the server to crash by dereferencing the null sub-pipeline.

Defensive priority

High

Recommended defensive actions

  • Apply the official patch or update to a fixed version of MongoDB Server 8.0.
  • Restrict access to aggregation pipeline execution to trusted users.
  • Monitor MongoDB Server logs for suspicious activity.

Evidence notes

Vendor: MongoDB (inferred from reference_domain_candidate).

Sources and references

Verified primary and authoritative sources

  • CVE-2026-9743 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-9743

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

  • CVE-2026-9743 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-9743

    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.