CVE-2026-114653: Silent client-side encryption bypass via unescaped field-name regex in CSFLE schema builder
A client-side encryption schema construction component in the MongoDB C# Driver places caller-supplied field identifiers into a position that is interpreted as a pattern expression, without normalizing or validating them. As a result, an application that designates certain fields for client-side field-level encryption may have the protection silently fail to apply, so data intended to be encrypted is stored and returned in cleartext; conversely, the rule may apply more broadly than intended. No user action is required to cause the condition, and any party with ordinary read access to the stored data — without possession of the encryption keys — can observe the unprotected values.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed?
Applications using the MongoDB C# Driver’s client-side encryption schema construction component are exposed when field identifiers supplied to that component are interpreted as pattern expressions rather than normalized or validated identifiers.
What access is needed to obtain data that should have been encrypted?
Once encryption fails to apply, any party with ordinary read access to the stored data can observe the affected values in cleartext. Possession of the encryption keys is not required.
How can we determine whether the issue has affected our data?
Check fields designated for client-side field-level encryption in stored documents and returned results. Cleartext values in fields expected to be encrypted indicate that the encryption rule did not apply; rules may also have applied to more fields than intended.