CVE-2026-26934: Kibana Denial of Service Vulnerability

CVE-2026-26934 Overview

A Denial of Service vulnerability exists in Kibana due to Improper Validation of Specified Quantity in Input (CWE-1284). This vulnerability allows an authenticated attacker with view-only privileges to cause a Denial of Service condition through Input Data Manipulation. An attacker can send a specially crafted, malformed payload causing excessive resource consumption and resulting in Kibana becoming unresponsive or crashing.

Critical Impact

Authenticated attackers with minimal privileges can render Kibana services unavailable, disrupting critical monitoring and observability operations for organizations relying on the Elastic Stack.

Affected Products

• Kibana versions prior to 8.19.12
• Kibana versions prior to 9.2.6
• Kibana versions prior to 9.3.1

Discovery Timeline

• 2026-02-26 - CVE CVE-2026-26934 published to NVD
• 2026-02-26 - Last updated in NVD database

Technical Details for CVE-2026-26934

Vulnerability Analysis

This vulnerability stems from improper validation of input quantities within Kibana's request processing mechanisms. The flaw allows authenticated users—even those with view-only privileges—to submit malformed payloads that bypass normal input validation checks. When Kibana processes these crafted requests, it fails to properly constrain resource allocation, leading to excessive memory or CPU consumption.

The attack surface is accessible over the network without requiring user interaction, making it relatively straightforward for authenticated attackers to exploit. The vulnerability specifically impacts availability, with no direct effect on data confidentiality or integrity.

Root Cause

The root cause is classified under CWE-1284: Improper Validation of Specified Quantity in Input. Kibana fails to adequately validate numerical or quantity-related input parameters before allocating resources or processing requests. This oversight allows attackers to specify excessively large or specially crafted values that trigger resource exhaustion conditions within the application.

Attack Vector

The attack requires network access and low-privilege authentication (view-only access is sufficient). An attacker constructs a malicious payload with manipulated input data designed to cause excessive resource consumption. When submitted to Kibana, the payload triggers an uncontrolled allocation of system resources, ultimately causing the service to become unresponsive or crash entirely.

The attack follows the CAPEC-153 (Input Data Manipulation) pattern, where the attacker leverages knowledge of how the application processes input to craft payloads that cause unintended behavior. Since view-only privileges are sufficient, the barrier to exploitation is relatively low in environments where Kibana access is broadly granted.

Detection Methods for CVE-2026-26934

Indicators of Compromise

• Unusual spikes in Kibana memory or CPU utilization without corresponding increases in legitimate user activity
• Repeated Kibana service crashes or unresponsive states following authenticated requests
• Anomalous request patterns from authenticated users with view-only roles containing unusually large or malformed input values

Detection Strategies

• Monitor Kibana application logs for error messages related to resource exhaustion, memory allocation failures, or request processing timeouts
• Implement request rate limiting and payload size validation at the reverse proxy or load balancer level
• Configure alerting for Kibana service health degradation, including response latency increases and availability drops

Monitoring Recommendations

• Enable detailed request logging in Kibana to capture payload characteristics for post-incident analysis
• Deploy application performance monitoring (APM) to track resource consumption patterns and identify anomalous behavior
• Establish baseline metrics for normal Kibana operation to facilitate rapid detection of DoS conditions

How to Mitigate CVE-2026-26934

Immediate Actions Required

• Upgrade Kibana to a patched version: 8.19.12, 9.2.6, or 9.3.1 or later
• Review and restrict user access permissions, ensuring only necessary users have Kibana access
• Implement network-level access controls to limit who can reach the Kibana service

Patch Information

Elastic has released security updates addressing this vulnerability in Kibana versions 8.19.12, 9.2.6, and 9.3.1. Organizations should upgrade to the appropriate patched version based on their current deployment. Detailed information is available in the Elastic Security Update Announcement.

Workarounds

• Deploy a web application firewall (WAF) or reverse proxy with request validation rules to filter potentially malicious payloads before they reach Kibana
• Implement strict rate limiting on authenticated API endpoints to reduce the impact of repeated exploitation attempts
• Consider temporarily restricting Kibana access to trusted IP ranges or VPN-connected users until patching is complete

# Example: Nginx rate limiting configuration for Kibana
limit_req_zone $binary_remote_addr zone=kibana_limit:10m rate=10r/s;

location / {
    limit_req zone=kibana_limit burst=20 nodelay;
    proxy_pass http://kibana_backend;
}