CVE-2026-26938: Kibana Workflows SSRF Vulnerability

CVE-2026-26938 Overview

CVE-2026-26938 is a high-severity template engine injection vulnerability in the Workflows feature of Kibana. This vulnerability stems from improper neutralization of special elements used in a template engine (CWE-1336), which could allow an authenticated attacker with the workflowsManagement:executeWorkflow privilege to read arbitrary files from the Kibana server filesystem and perform Server-Side Request Forgery (SSRF) attacks via code injection.

Critical Impact

Authenticated attackers can leverage this vulnerability to access sensitive configuration files, credentials, and internal network resources through arbitrary file read and SSRF capabilities.

Affected Products

• Kibana (versions prior to 9.3.1)
• Elastic Stack deployments utilizing the Workflows feature
• Self-managed and cloud-hosted Kibana instances with Workflows enabled

Discovery Timeline

• 2026-02-26 - CVE-2026-26938 published to NVD
• 2026-02-26 - Last updated in NVD database

Technical Details for CVE-2026-26938

Vulnerability Analysis

This vulnerability exists within the Workflows component of Kibana, where user-supplied input is processed by a template engine without proper sanitization. Template engines are commonly used to dynamically generate content by substituting placeholders with values. However, when special template syntax elements are not properly neutralized, attackers can inject malicious template directives that execute on the server side.

The exploitation of this vulnerability requires authentication and specific privileges—namely the workflowsManagement:executeWorkflow permission. This privilege gate limits the attack surface to users who have been explicitly granted workflow execution capabilities, though it does not mitigate the severity of the underlying vulnerability.

Successful exploitation enables two primary attack vectors: arbitrary file read operations that can expose sensitive data such as configuration files, API keys, and credentials stored on the Kibana server, and SSRF attacks that allow the attacker to make requests from the server to internal network resources that would otherwise be inaccessible.

Root Cause

The root cause of CVE-2026-26938 is the improper neutralization of special elements within the template engine used by the Kibana Workflows feature. When processing workflow definitions or parameters, the application fails to adequately sanitize or escape template syntax characters before passing them to the template rendering engine. This allows attackers to break out of the intended template context and inject arbitrary template directives that are then executed server-side.

Attack Vector

The attack is network-accessible and requires an authenticated session with the workflowsManagement:executeWorkflow privilege. An attacker would craft a malicious workflow or workflow input containing specially formatted template injection payloads. When this payload is processed by Kibana's template engine, the injected code executes with the privileges of the Kibana server process.

For arbitrary file read, the attacker injects template directives that access the filesystem, retrieving the contents of sensitive files such as /etc/passwd, Kibana configuration files, or stored credentials.

For SSRF attacks, the injected template code triggers HTTP requests to internal network endpoints, cloud metadata services (e.g., http://169.254.169.254/), or other services accessible only from the server's network position. This can lead to further exploitation of internal systems or exposure of cloud infrastructure credentials.

Detection Methods for CVE-2026-26938

Indicators of Compromise

• Unusual workflow execution patterns from users with the workflowsManagement:executeWorkflow privilege
• Kibana server logs showing access to sensitive system files (e.g., /etc/passwd, kibana.yml, .env files)
• Outbound HTTP/HTTPS requests from the Kibana server to unexpected internal IP ranges or cloud metadata endpoints
• Template syntax patterns in workflow definitions or input parameters (e.g., {{, ${, <%)

Detection Strategies

• Monitor Kibana audit logs for workflow execution events from newly privileged or suspicious user accounts
• Implement network-level monitoring to detect SSRF attempts, particularly connections to internal RFC1918 addresses, localhost, or cloud metadata services
• Deploy file integrity monitoring on the Kibana server to alert on unexpected file access patterns
• Analyze workflow input fields and definitions for common template injection patterns

Monitoring Recommendations

• Enable enhanced Kibana audit logging and forward logs to your SIEM for correlation
• Configure network segmentation rules to restrict outbound connections from Kibana servers
• Implement alerting on access to workflow management APIs from unusual source IPs or during off-hours
• Regularly review and audit user permissions, specifically the workflowsManagement:executeWorkflow privilege

How to Mitigate CVE-2026-26938

Immediate Actions Required

• Upgrade Kibana to version 9.3.1 or later, which addresses this vulnerability
• Review and restrict the workflowsManagement:executeWorkflow privilege to only essential users
• Audit all existing workflows for potentially malicious template syntax
• If immediate patching is not possible, consider temporarily disabling the Workflows feature

Patch Information

Elastic has released a security update (ESA-2026-17) that addresses this vulnerability. Organizations should upgrade to Kibana version 9.3.1 or later to remediate CVE-2026-26938. For detailed information, refer to the Elastic Security Update ESA-2026-17.

Workarounds

• Implement network-level controls to prevent the Kibana server from making outbound connections to internal network segments and cloud metadata services
• Apply the principle of least privilege by removing the workflowsManagement:executeWorkflow permission from non-essential users
• Deploy a Web Application Firewall (WAF) configured to detect and block common template injection patterns
• Consider running Kibana in a sandboxed environment with restricted filesystem access

# Configuration example - Restrict outbound connections using iptables
# Block Kibana server from accessing internal networks and cloud metadata
iptables -A OUTPUT -m owner --uid-owner kibana -d 169.254.169.254 -j DROP
iptables -A OUTPUT -m owner --uid-owner kibana -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -m owner --uid-owner kibana -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -m owner --uid-owner kibana -d 192.168.0.0/16 -j DROP