A critical vulnerability, CVE-2026-49252, has been identified in the deepstream platform, affecting versions prior to 10.0.5. This vulnerability enables authenticated users with write permissions to any record to escalate privileges through prototype pollution. The CVSS score of 9.9 indicates a severe risk level, as exploitation could lead to unauthorized access and control over system resources. The deepstream platform facilitates data synchronization, messaging, and RPCs at scale, making it a critical component for many applications. Organizations utilizing affected versions should prioritize upgrading to version 10.0.5 or later to mitigate this risk. The vulnerability arises from improper handling of input data during the processing of records, allowing malicious actors to inject arbitrary properties into object prototypes. This can result in unintended behavior, including privilege escalation. As the severity is classified as critical, immediate action is recommended to prevent potential exploitation. Users are advised to review their current version and apply the necessary patches as soon as possible. This advisory underscores the importance of maintaining up-to-date software to address known vulnerabilities and protect against potential threats.