Letta API Unauthenticated Remote Code Execution via Default PostgreSQL

Executive Summary

CVE-2026-77936 affects Letta versions up to 0.16.8 due to an insecure default configuration in compose.yaml. The LETTA_SERVER_SECURE setting is disabled, disabling password middleware and exposing all API routes without authentication. Additionally, the PostgreSQL port is exposed with default credentials. Attackers can exploit this to run arbitrary Python code, manage admin users, or execute OS commands via specific API endpoints.

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Detection Guidance

Check if Letta is running with the insecure compose.yaml configuration by inspecting the Docker Compose file for exposed PostgreSQL port 5432 and unauthenticated API endpoints. Verify if LETTA_SERVER_SECURE is disabled in environment variables.

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Impact Analysis

This vulnerability allows remote attackers to gain full control over the Letta server and PostgreSQL database. They can execute arbitrary Python code, manipulate user accounts, or run operating system commands. Unauthorized access to sensitive data stored in the database is also possible, leading to potential data breaches or system compromise.

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Compliance Impact

This vulnerability likely violates compliance requirements for GDPR and HIPAA due to unauthorized data access and potential data breaches. GDPR mandates strict data protection and breach notification, while HIPAA requires safeguards for protected health information. The lack of authentication and exposed database credentials directly contravene these standards.

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Mitigation Strategies

Update Letta to a version beyond 0.16.8 where LETTA_SERVER_SECURE is enabled by default. Ensure PostgreSQL is not exposed externally and change default credentials. Restrict API access to trusted networks only.

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