CVE-2026-126818: Mongoid 9.1.1 incomplete CVE-2026-93764 fix stores descendant-only encrypted fields in plaintext
A Ruby object-document mapper does not apply its automatic field-level encryption configuration to certain fields when the data model uses class inheritance. Values the application designated for encryption are written to the database in readable form without any error or warning. A database account holding only read access to the application's collections, and no access to the encryption key store, may obtain those values.
Affected Software
Event History
Frequently Asked Questions
Which applications are exposed to plaintext storage?
Applications using Mongoid automatic field-level encryption are exposed when an encrypted field is defined only on a descendant class in an inherited data model. Those field values can be written to the database in readable form without an error or warning.
What access does an attacker need to obtain the affected values?
An attacker needs read access to the application's database collections. Access to the encryption key store is not required.
How can teams determine whether they are already affected?
Review inherited Mongoid models for fields configured for automatic encryption only on descendant classes, then inspect stored documents for those field values. Affected values may be present in readable plaintext despite being designated for encryption.