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CVE-2026-126982 Remote code execution via generic-type allow-list bypass in BSON object deserialization

7.7 highEPSS 0.3%

High (7.7) in mongodb c# driver. EPSS 0.3% estimated probability of exploitation activity in the next 30 days.

On this page
A type allow-list bypass in the BSON serialization library of the MongoDB C# Driver allows a type-restriction check to be circumvented when polymorphic data is deserialized into loosely typed members. An unauthorized party who can supply or plant BSON/JSON data that the application later deserializes can cause the application process to instantiate .NET types outside the intended allow-list and populate them with unauthorized party-controlled values. In applications that contain a suitable gadget type, this can lead to arbitrary code execution in the context of the application, with corresponding loss of confidentiality, integrity, and availability. No special privileges beyond the ability to introduce data the application reads are required.

Severity

CVSS 4.0

7.7 high
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5 high
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
0.3% estimated probability of exploitation activity in the next 30 days; 23rd percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CWE
CWE-502 Deserialization of Untrusted Data
OWASP Top 10
A08:2025 Software or Data Integrity Failures
Published
Modified
Assigned by
mongodb (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

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Affected

  • mongodb:c# driver

Versions

From the CNA's record in the CVE List.

ProductAffected
MongoDB C# Driverfrom 3.2.0 before 3.14.0

Attack patterns (CAPEC)

  • CAPEC-586 Object Injection Likelihood: Medium · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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