CVE-2026-25957: Cube Semantic Layer DoS Vulnerability

CVE-2026-25957 Overview

CVE-2026-25957 is a Denial of Service vulnerability affecting Cube, a semantic layer for building data applications. The vulnerability exists in versions from 1.1.17 to before 1.5.13 and 1.4.2, where it is possible to make the entire Cube API unavailable by submitting a specially crafted request to a Cube API endpoint. This improper exception handling vulnerability (CWE-755) can result in complete service disruption for applications relying on the Cube semantic layer.

Critical Impact

Attackers can render the entire Cube API unavailable through specially crafted requests, disrupting all data applications dependent on the semantic layer.

Affected Products

• Cube versions 1.1.17 to before 1.5.13
• Cube versions 1.1.17 to before 1.4.2

Discovery Timeline

• 2026-02-09 - CVE CVE-2026-25957 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2026-25957

Vulnerability Analysis

This vulnerability stems from improper handling of exceptional conditions (CWE-755) within the Cube API. When a specially crafted request is submitted to an API endpoint, the application fails to properly handle the malformed input, resulting in a denial of service condition. The vulnerability requires network access and low-privilege authentication to exploit, but no user interaction is needed.

The impact is primarily on availability, with no direct effect on confidentiality or integrity. However, the complete unavailability of the Cube API can have significant downstream effects on all data applications that depend on this semantic layer for their operations.

Root Cause

The root cause is improper exception handling (CWE-755: Improper Handling of Exceptional Conditions) within the Cube API request processing logic. When certain malformed or specially crafted requests are received, the application does not gracefully handle the exception, leading to a crash or hung state that renders the entire API unavailable.

Attack Vector

The attack is conducted over the network and requires authenticated access with low privileges. An attacker with valid credentials can submit a specially crafted HTTP request to any Cube API endpoint. The malformed request triggers an unhandled exception in the request processing pipeline, causing the API service to become unavailable to all users.

The vulnerability does not require any user interaction, making it straightforward to exploit once an attacker has authenticated access to the API. For detailed technical information about the vulnerability mechanism, refer to the GitHub Security Advisory.

Detection Methods for CVE-2026-25957

Indicators of Compromise

• Sudden unavailability of Cube API endpoints following authenticated requests
• Application crash logs or error messages indicating unhandled exceptions in the API layer
• Repeated failed health checks or service restarts for the Cube application
• Unusual patterns of API requests preceding service disruptions

Detection Strategies

• Monitor Cube API availability and response times for anomalous degradation patterns
• Implement logging for malformed or unusual API requests that result in errors
• Set up alerts for Cube service crashes, restarts, or health check failures
• Review authentication logs for suspicious activity from low-privilege accounts

Monitoring Recommendations

• Deploy application performance monitoring (APM) to detect service availability issues
• Configure centralized logging to capture API request patterns and exception details
• Implement real-time alerting for Cube API downtime or degraded performance
• Monitor system resources (CPU, memory) for the Cube application to detect anomalous resource usage

How to Mitigate CVE-2026-25957

Immediate Actions Required

• Upgrade Cube to version 1.5.13 or 1.4.2 or later immediately
• Review access controls and audit authenticated users with API access
• Implement rate limiting on Cube API endpoints to reduce DoS impact
• Enable comprehensive logging to detect and investigate exploitation attempts

Patch Information

This vulnerability is fixed in Cube versions 1.5.13 and 1.4.2. Organizations should prioritize upgrading to these patched versions. Detailed patch information is available in the GitHub Security Advisory.

Workarounds

• Implement a Web Application Firewall (WAF) to filter potentially malicious API requests
• Restrict API access to trusted networks or IP ranges where possible
• Enable request validation and input sanitization at the reverse proxy level
• Consider implementing circuit breaker patterns to automatically recover from service disruptions

# Example: Implement rate limiting with nginx reverse proxy
# Add to your nginx configuration for Cube API endpoints
limit_req_zone $binary_remote_addr zone=cube_api:10m rate=10r/s;

location /cubejs-api/ {
    limit_req zone=cube_api burst=20 nodelay;
    proxy_pass http://cube-backend;
}