CVE-2025-25015: Elastic Kibana RCE Vulnerability

CVE-2025-25015 Overview

CVE-2025-25015 is a critical prototype pollution vulnerability in Elastic Kibana that enables arbitrary code execution through crafted file uploads and specifically crafted HTTP requests. This vulnerability affects the core JavaScript object prototype chain, allowing attackers to inject malicious properties that propagate throughout the application and ultimately lead to remote code execution.

The severity of this vulnerability varies based on Kibana version and user privileges. In Kibana versions >= 8.15.0 and < 8.17.1, this vulnerability is exploitable by users with the basic Viewer role, significantly expanding the attack surface. In versions 8.17.1 and 8.17.2, exploitation requires elevated privileges including fleet-all, integrations-all, and actions:execute-advanced-connectors.

Critical Impact

This prototype pollution vulnerability allows authenticated attackers to achieve arbitrary code execution on Kibana servers, potentially compromising the entire Elastic Stack infrastructure and any data accessible through the platform.

Affected Products

• Elastic Kibana versions >= 8.15.0 and < 8.16.6
• Elastic Kibana versions >= 8.17.0 and < 8.17.3

Discovery Timeline

• 2025-03-05 - CVE-2025-25015 published to NVD
• 2025-10-02 - Last updated in NVD database

Technical Details for CVE-2025-25015

Vulnerability Analysis

This vulnerability is classified as CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes), commonly known as prototype pollution. Prototype pollution occurs when an attacker can modify the prototype of a base object, such as Object.prototype in JavaScript. Since JavaScript uses prototype-based inheritance, any modifications to a base object's prototype will be inherited by all objects derived from it.

In Kibana's case, the vulnerability manifests through improper handling of user-supplied input during file upload operations and HTTP request processing. The attack can be executed remotely over the network by authenticated users, requires low complexity to exploit, and needs no user interaction. The vulnerability has a changed scope, meaning successful exploitation can impact resources beyond the vulnerable component itself, affecting confidentiality, integrity, and availability of the system.

Root Cause

The root cause stems from insufficient input validation and sanitization in Kibana's request processing logic. When handling file uploads and HTTP requests, the application fails to properly sanitize object keys and values, allowing attackers to inject special properties like __proto__, constructor, or prototype that modify the behavior of base JavaScript objects. This pollution propagates through the application's runtime, enabling code execution when the tainted properties are later accessed in security-sensitive contexts.

Attack Vector

The attack vector involves network-accessible exploitation through authenticated sessions. Attackers craft malicious file uploads or HTTP requests containing prototype pollution payloads. The exploitation path differs based on version:

For Kibana 8.15.0 to < 8.17.1:

• Any user with the Viewer role can exploit this vulnerability
• The low privilege requirement significantly increases risk exposure

For Kibana 8.17.1 and 8.17.2:

• Exploitation requires a combination of elevated privileges: fleet-all, integrations-all, and actions:execute-advanced-connectors
• This limits the attack surface to administrative users

The attacker sends specially crafted payloads that pollute the JavaScript prototype chain, ultimately achieving arbitrary code execution on the Kibana server. This can lead to complete system compromise, data exfiltration, lateral movement within the network, and potential compromise of the connected Elasticsearch cluster.

Detection Methods for CVE-2025-25015

Indicators of Compromise

• Unusual HTTP requests to Kibana endpoints containing __proto__, constructor.prototype, or similar prototype pollution strings in request bodies or file uploads
• Unexpected process spawning from the Kibana Node.js process
• Anomalous file system access patterns from the Kibana service account
• Network connections from Kibana server to unexpected external destinations

Detection Strategies

• Monitor HTTP request logs for payloads containing prototype pollution indicators such as __proto__, constructor, or prototype property assignments
• Implement Web Application Firewall (WAF) rules to detect and block requests containing prototype pollution patterns
• Deploy runtime application self-protection (RASP) solutions to detect prototype pollution attempts
• Review Kibana audit logs for suspicious file upload activities and API requests from Viewer-role users

Monitoring Recommendations

• Enable comprehensive logging for all Kibana API endpoints, particularly file upload and Fleet-related endpoints
• Configure SIEM rules to alert on prototype pollution patterns in request payloads
• Monitor for unauthorized privilege escalation or unexpected code execution from the Kibana service
• Implement anomaly detection for Kibana process behavior to identify post-exploitation activities

How to Mitigate CVE-2025-25015

Immediate Actions Required

• Upgrade Kibana to version 8.17.3 or 8.16.6 immediately to remediate this vulnerability
• If immediate patching is not possible, restrict access to Kibana to only trusted users and networks
• Review and audit user roles, removing unnecessary Viewer access and elevated Fleet/Integrations privileges
• Implement network segmentation to limit the blast radius of potential exploitation

Patch Information

Elastic has released security updates addressing this vulnerability. Users should upgrade to Kibana version 8.17.3 or 8.16.6 depending on their deployment branch. For detailed patch information and upgrade instructions, refer to the Kibana 8.17.3/8.16.6 Security Update (ESA-2025-06).

Workarounds

• For versions 8.17.1 and 8.17.2, review and restrict users who have the combined privileges of fleet-all, integrations-all, and actions:execute-advanced-connectors
• For versions prior to 8.17.1, consider temporarily restricting Viewer role access or placing Kibana behind additional authentication layers
• Deploy WAF rules to filter requests containing prototype pollution payloads as a defense-in-depth measure
• Consider temporarily disabling file upload functionality if business requirements permit

# Verify Kibana version and plan upgrade
# Check current Kibana version
curl -X GET "http://localhost:5601/api/status" -H "kbn-xsrf: true" | jq '.version.number'

# After upgrading, verify the patched version is running
# Expected: 8.17.3 or 8.16.6 (or later)