CVE-2026-114655

libmongocrypt builds requests to external key management services (AWS, Azure and GCP) by inserting values from key vault documents, KMS provider configuration and KMS responses into request lines, headers and signed request bodies without validating or encoding them for each context. A user with write access to the key vault collection can alter the structure of these requests, including adding members to request bodies and token claims that the library then signs with the application's credentials. This may result in key management operations being performed with parameters the application did not intend.

The organization may experience unauthorized key management operations, potentially leading to key integrity compromise or unexpected actions in cloud services.

Update libmongocrypt to a patched version. Restrict write access to the key vault collection to trusted entities only and monitor for unusual key management operations.