CVE-2026-81521

Cross-database write retargeting via unvalidated dotted database name in Client.BulkWrite in the MongoDB Go Driver

MEDIUM
6.5
CVSS Score
Published: August 27, 2026 at 06:31 PM UTC
Updated: October 6, 2026 at 07:18 PM UTC
1 product affected across 1 vendorGO Driver

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An application that passes untrusted input as a database name could therefore have the write directed at a database and collection other than the ones it intended. Only the Client.BulkWrite API is affected.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.1.0 ≤ v < 2.8.22.1.0
Affected range stops below 2.8.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMmongodb
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-99

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