CVE-2026-84966

Unverifiable BSON builder process termination

Published Sep 3, 2026 · Updated Sep 3, 2026

MongoDB .NET/C# Driver is listed as affected, but no published advisory links it to the reported BSON builder flaw. The supplied source text instead attributes an incorrect length conversion and out-of-bounds read on an oversized, nonterminated field name to the MongoDB C++ Driver. Without an authoritative record reconciling the product and version range, impact and reachability for the .NET/C# Driver remain unverifiable.

CVSS severityUnavailable
Unscored
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

MongoDB .NET/C# Driver is listed as affected, but no published advisory links it to the reported BSON builder flaw. The supplied source text instead attributes an incorrect length conversion and out-of-bounds read on an oversized, nonterminated field name to the MongoDB C++ Driver. Without an authoritative record reconciling the product and version range, impact and reachability for the .NET/C# Driver remain unverifiable.

The record

CVE
CVE-2026-84966
Published
Sep 3, 2026
Updated
Sep 3, 2026
Vendor
MongoDB
Product
MongoDB .NET/C# Driver
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.2.0 <4.5.2

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

MongoDB · MongoDB .NET/C# Driverversion=3.2.0 <4.5.2

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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