MongoDB C# Driver up to 3.13.x Serialization input validation

Summaryinfo

A vulnerability identified as very critical has been detected in MongoDB C# Driver up to 3.13.x. The affected element is an unknown function of the component Serialization. This manipulation causes input validation. This vulnerability is registered as CVE-2026-126982. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in MongoDB C# Driver up to 3.13.x and classified as very critical. Affected by this vulnerability is some unknown functionality of the component Serialization. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at jira.mongodb.org. This vulnerability is known as CVE-2026-126982 since 11/12/2026. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD at the moment (estimation calculated on 11/13/2026).

Upgrading to version 3.14.0 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Database Software

Vendor

• MongoDB

Name

• C# Driver

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13

License

• open-source

CPE 2.3info

• 🔒
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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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