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CVE-2026-9100 MongoDB, Inc. CVE debrief

CVE-2026-9100 describes a flaw in the MongoDB C Driver’s legacy GridFS API where malformed file metadata from the database is not validated adequately. If an application reads a crafted GridFS document through that legacy API, the result can be a denial of service crash (division-by-zero) or a silent memory disclosure via out-of-bounds read. NVD published the CVE on 2026-05-20 and listed the issue as Awaiting Analysis at the time of the source update.

Vendor
MongoDB, Inc.
Product
C Driver
CVSS
MEDIUM 6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-20
Original CVE updated
2026-05-20
Advisory published
2026-05-20
Advisory updated
2026-05-20

Who should care

Teams running applications that read GridFS content through the legacy MongoDB C Driver API, especially services that process database-controlled metadata in production. Security and platform owners should also care if the driver is used in exposed or multi-tenant services, because the impact includes both service interruption and possible process memory disclosure.

Technical summary

According to the CVE description, malformed GridFS file metadata stored in the database can reach the MongoDB C Driver legacy GridFS reader without sufficient validation. The malformed input may drive a division-by-zero path that crashes the application, or an out-of-bounds read that can leak process memory contents. The supplied weakness mapping identifies CWE-1285, and the NVD record cites a MongoDB Jira issue (CDRIVER-6281) as the source reference.

Defensive priority

Medium priority. The issue is externally triggerable through data already present in a GridFS collection, and the impact includes both availability loss and potential information exposure. Prioritize environments that rely on the legacy GridFS API over newer code paths, and treat any service that reads untrusted or database-sourced GridFS metadata as higher risk.

Recommended defensive actions

  • Inventory applications and services that use the MongoDB C Driver legacy GridFS API.
  • Check whether any code paths read GridFS documents that may be writable by less-trusted users or upstream systems.
  • Apply the vendor fix or update once MongoDB publishes the remediated driver version and release notes.
  • If immediate patching is not possible, reduce exposure by limiting who can write to the relevant GridFS collections and by avoiding legacy GridFS read paths where feasible.
  • Monitor for crashes or anomalous responses in services that process GridFS metadata, since the flaw can manifest as a division-by-zero failure or memory disclosure.
  • Review incident handling for possible memory exposure if the affected service handled sensitive in-process data.

Evidence notes

Primary evidence comes from the supplied CVE description and the official NVD record for CVE-2026-9100. The NVD source metadata references MongoDB Jira ticket CDRIVER-6281 and records the weakness as CWE-1285. The record was published on 2026-05-20 and updated the same day; the supplied timeline should be used for timing context, not generation or review time.

Official resources

Publicly disclosed through the official CVE/NVD channels on 2026-05-20. The supplied NVD snapshot lists the vulnerability status as Awaiting Analysis, so remediation details may still evolve as vendor analysis completes.