Authenticated users of Lemur can influence the ACME authority acme_url parameter, which the application uses to construct outbound requests. This lack of server‑side destination validation allows an attacker to direct Lemur to send HTTP requests to internal services, including cloud instance metadata endpoints, thereby extracting credentials that the host process is authorized to use. The same authenticated session also suffers an IDOR flaw: the creator‑equality authorization model permits users to retain access to certificate key material after ownership or role changes, and audit logs lack the necessary context to detect such misuse. Together these weaknesses provide an attacker with long‑term Amazon Web Services IAM credentials and the ability to export private PKI keys, compromising both cloud infrastructure and secure TLS communication.

The bug affects Netflix Lemur versions prior to 1.9.2. The fix was released in the 1.9.2 release, so any instance running 1.9.1 or earlier is vulnerable.

The CVSS score of 9.9 indicates critical severity. The EPSS score is not available, but the high CVSS combined with the lack of mitigation suggests a high likelihood of exploitation in environments where Lemur is exposed to unauthenticated or internal users. The vulnerability is not listed in the CISA KEV catalog, but it remains in the public advisory. Attackers would need authenticated access to Lemur and the ability to set the acme_url value; from there, they can steer the application to access internal endpoints and export private key material. This creates a broad attack surface for attackers seeking to compromise cloud credentials and persistent private keys.