What’s Vulnerable › Vulnerabilities

CVE-2026-114654: BSON output corruption via out-of-range binary subtype bypassing UUID and OldBinary guards

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-22 · updated 2026-10-30
• Weakness: CWE-681

Description

A numeric-type conversion flaw in the BSON handling library of the MongoDB C# Driver allows an out-of-range binary subtype value supplied through untrusted textual input to bypass the library's binary-element integrity checks. When such a value is later encoded, it is narrowed to a smaller wire representation, producing binary elements that misdeclare their type or length. An unauthenticated party able to supply text parsed by an affected application can cause it to emit and persist malformed binary data, which subsequent readers either reject with an error or silently interpret as shorter than the data that was validated.

Affected products

• MongoDB C# Driver: from 2.0.0 before 3.13.0 — fixed in 3.13.0

How to fix

Upgrade to a fixed version: MongoDB C# Driver 3.13.0. Check the vendor advisory for mitigations.

References

• https://github.com/mongodb/mongo-csharp-driver/releases/tag/v3.13.0
• https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-5h2q-6c9r-7x25
• https://jira.mongodb.org/browse/CSHARP-6166
• https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-5h2q-6c9r-7x25

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