Apache Livy CVE-2025-66249

The CVSS v3.1 vector (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L) indicates moderate real-world risk with several mitigating factors. The Network Attack Vector (AV:N) and Low Attack Complexity (AC:L) indicate the vulnerability is remotely exploitable without special conditions, but the requirement for prior authentication (PR:L) significantly reduces the threat surface. The impact is bounded (Confidentiality, Integrity, and Availability all rated Low with Scope Unchanged) rather than critical or high, limiting potential damage from a single exploitation. The conditional nature of the vulnerability—requiring non-default configuration—further narrows the affected population to organizations that have explicitly customized their Livy deployment. Without confirmed EPSS data or public POC availability noted in standard vulnerability databases, and absent KEV (Known Exploited Vulnerability) status, this appears to be a moderate-priority issue suitable for standard patch management cycles rather than emergency response. Organizations using default Livy configurations are not exposed. The real risk level depends on deployment context: multi-tenant Livy instances with untrusted users pose higher risk than single-tenant or administratively-controlled deployments.

An attacker with valid Livy API credentials (e.g., a disgruntled employee or compromised service account) crafts a malicious request to the file upload or execution endpoint, injecting path traversal sequences to escape the configured whitelist directory. For example, if the whitelist permits '/opt/livy/uploads', the attacker submits a file path like '/opt/livy/uploads/../../etc/passwd' or uses symbolic links within the whitelist to reference sensitive system files. With Low Attack Complexity and Low privileges required, the attacker can exploit this within minutes of gaining initial credentials, potentially exfiltrating configuration files containing database credentials or Spark cluster secrets, or deploying malicious Spark jobs that read/modify files across the Livy server's filesystem. The bounded impact means full system compromise is unlikely, but lateral movement or data exfiltration within the organization becomes feasible.