CVE-2026-49087: Kibana Denial of Service Vulnerability

CVE-2026-49087 Overview

CVE-2026-49087 is a resource exhaustion vulnerability in Elastic Kibana that allows an authenticated user to trigger a denial of service. The flaw stems from Allocation of Resources Without Limits or Throttling [CWE-770]. An attacker submits a specially crafted bulk deletion request that consumes excessive server resources. The result is Kibana unavailability for legitimate users. Elastic addressed the issue in security update ESA-2026-49, released for Kibana versions 8.19.15 and 9.3.4.

Critical Impact
An authenticated attacker can render Kibana unavailable by submitting a single crafted bulk deletion request that exhausts server resources.

Affected Products

Elastic Kibana versions prior to 8.19.15
Elastic Kibana versions prior to 9.3.4
Deployments where authenticated users can access bulk deletion functionality

Discovery Timeline

2026-07-01 - CVE-2026-49087 published to NVD
2026-07-01 - Last updated in NVD database

Technical Details for CVE-2026-49087

Vulnerability Analysis

The vulnerability resides in Kibana's bulk deletion request handler. The endpoint accepts deletion requests without enforcing bounds on the volume of items processed or the resources consumed during processing. An authenticated user with valid credentials can craft a bulk deletion payload that forces Kibana to allocate excessive memory, CPU, or I/O resources. This aligns with CAPEC-130 (Excessive Allocation), where an attacker abuses a legitimate API to force uncapped resource consumption.

Root Cause

The root cause is missing input validation and throttling on the bulk deletion API [CWE-770]. Kibana does not enforce reasonable upper bounds on the size or complexity of bulk deletion payloads. It also lacks per-user rate limiting to constrain the frequency of expensive operations. When a large or complex payload is processed, resource consumption grows unchecked until the service degrades or becomes unresponsive.

Attack Vector

Exploitation requires network access to Kibana and valid authenticated credentials. The attacker does not need elevated privileges beyond a standard authenticated role that can invoke the bulk deletion functionality. No user interaction is required. A single crafted HTTP request to the vulnerable endpoint can trigger the resource exhaustion condition. Because the attack targets availability only, confidentiality and integrity remain unaffected.

No verified public proof-of-concept code is available. Refer to the Elastic Security Update ESA-2026-49 for vendor-provided technical details.

Detection Methods for CVE-2026-49087

Indicators of Compromise

Unusually large HTTP POST or DELETE payloads targeting Kibana bulk deletion endpoints
Sudden spikes in Kibana process memory or CPU utilization correlated with a single authenticated session
HTTP 5xx responses or request timeouts from the Kibana API following bulk operations
Repeated bulk deletion requests originating from a single user account within a short window

Detection Strategies

Monitor Kibana access logs for bulk deletion API calls with abnormally large request bodies or item counts
Correlate authenticated user activity with resource utilization metrics on Kibana nodes
Alert on Kibana process restarts, out-of-memory events, or unresponsive health checks

Monitoring Recommendations

Ingest Kibana audit logs and web server access logs into a centralized SIEM for correlation
Track baseline request sizes and rates per authenticated user to surface outliers
Configure availability monitoring for Kibana endpoints with alerting on prolonged latency or downtime

How to Mitigate CVE-2026-49087

Immediate Actions Required

Upgrade Kibana to version 8.19.15, 9.3.4, or later as specified in ESA-2026-49
Review and restrict role assignments that grant bulk deletion privileges to authenticated users
Enable Kibana audit logging to capture bulk operation activity for retrospective analysis

Patch Information

Elastic released fixed versions in security update ESA-2026-49. Kibana 8.19.15 and Kibana 9.3.4 contain the remediation. Refer to the Elastic Security Update ESA-2026-49 for the full advisory and upgrade guidance.

Workarounds

Place a reverse proxy or web application firewall in front of Kibana to enforce request size limits and per-user rate limiting on the bulk deletion endpoint
Restrict Kibana access to trusted networks and reduce the number of accounts with deletion privileges until patching is complete
Monitor resource utilization on Kibana hosts and configure automated restart of unresponsive instances as a temporary safeguard

bash

# Example nginx reverse proxy configuration to limit request body size and rate
http {
    limit_req_zone $binary_remote_addr zone=kibana_api:10m rate=10r/s;

    server {
        listen 443 ssl;
        server_name kibana.example.com;

        client_max_body_size 1m;

        location / {
            limit_req zone=kibana_api burst=20 nodelay;
            proxy_pass http://kibana_backend:5601;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
        }
    }
}