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CVE-2026-9748 MongoDB CVE debrief

CVE-2026-9748 is a HIGH severity vulnerability in MongoDB. The $_internalConvertBucketIndexStats stage used PauseExecution as a way to signal 'skip this document' when an index stats conversion failed. However, PauseExecution is not a general-purpose skip mechanism but rather a TeeBuffer-internal signal used solely by $facet to coordinate its sub-pipelines. When this stage is placed before $facet in a pipeline, TeeBuffer receives the unexpected PauseExecution from upstream and hits a hard invariant assertion, crashing mongod.

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 should be aware of this vulnerability and take action to mitigate it.

Technical summary

The $_internalConvertBucketIndexStats stage in MongoDB incorrectly used PauseExecution to signal 'skip this document' when an index stats conversion failed. This can cause a crash when the stage is placed before $facet in a pipeline.

Defensive priority

HIGH

Recommended defensive actions

  • Apply the patch or update to a version of MongoDB that fixes this issue.
  • Review and update pipeline configurations to avoid placing the $_internalConvertBucketIndexStats stage before $facet.

Evidence notes

Evidence suggests that this vulnerability was introduced in an unspecified version of MongoDB.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-9748 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-9748

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

  • CVE-2026-9748 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-9748

    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.