CVE-2026-56255 Overview
CVE-2026-56255 is a denial of service vulnerability in Capgo versions before 12.128.2. The flaw resides in the POST /app/demo endpoint, which lacks rate limiting and quota enforcement. Authenticated users with organization write permissions can repeatedly invoke the endpoint to create unlimited demo applications. Each request generates approximately 138 database write operations, amplifying the impact on backend infrastructure. The vulnerability falls under [CWE-770] (Allocation of Resources Without Limits or Throttling) and can degrade service performance, increase operational costs, and destabilize the platform.
Critical Impact
Authenticated attackers can exhaust database resources by repeatedly invoking the demo creation endpoint, with each call triggering roughly 138 write operations against the backend.
Affected Products
- Capgo versions prior to 12.128.2
- The POST /app/demo API endpoint
- Capgo backend database infrastructure
Discovery Timeline
- 2026-06-22 - CVE-2026-56255 published to NVD
- 2026-06-23 - Last updated in NVD database
Technical Details for CVE-2026-56255
Vulnerability Analysis
The vulnerability stems from missing resource allocation controls on the POST /app/demo endpoint in Capgo. The endpoint provisions demonstration applications for authenticated users carrying organization write permissions. Each invocation triggers approximately 138 database write operations to populate the demo application's records. Capgo does not enforce per-user, per-organization, or global quotas on demo creation. Capgo also omits rate limiting on this endpoint, allowing rapid repeated calls. Attackers with valid credentials and the required role can script unlimited invocations. The cumulative database writes degrade performance, inflate storage and compute costs, and may destabilize dependent services.
Root Cause
The root cause is the absence of throttling and quota enforcement on a resource-intensive write operation. The endpoint trusts authenticated callers without bounding the volume of work they can request. This aligns with the [CWE-770] weakness pattern, where resources are allocated without limits.
Attack Vector
The attack requires network access to the Capgo API and an authenticated session with organization write permissions. The attacker issues repeated POST /app/demo requests in a loop. No user interaction is required and the attack complexity is low. The impact is limited to availability, with confidentiality and integrity unaffected. The vulnerability does not enable remote code execution or data disclosure.
No verified exploitation code is published. See the VulnCheck Denial of Service Advisory and the GitHub Security Advisory for technical details.
Detection Methods for CVE-2026-56255
Indicators of Compromise
- High-frequency POST /app/demo requests originating from a single authenticated user or API token within a short time window.
- Sudden growth in the number of demo applications associated with a single organization.
- Spikes in database write operations and storage utilization without a corresponding increase in legitimate user activity.
Detection Strategies
- Aggregate API access logs by endpoint and user identity to flag abnormal request rates against /app/demo.
- Baseline normal demo creation volumes per organization and alert on statistical deviations.
- Correlate authentication events with backend write operation counts to identify amplification patterns.
Monitoring Recommendations
- Track database write throughput, connection pool saturation, and query latency on the Capgo backend.
- Monitor cloud cost telemetry for unexpected billing spikes tied to write-heavy workloads.
- Forward Capgo application and infrastructure logs to a centralized analytics platform for long-term trend analysis.
How to Mitigate CVE-2026-56255
Immediate Actions Required
- Upgrade Capgo to version 12.128.2 or later, which introduces controls on demo application creation.
- Audit existing demo applications and remove entries created by suspicious or unauthorized accounts.
- Review which user accounts hold organization write permissions and revoke unnecessary privileges.
Patch Information
The vulnerability is resolved in Capgo 12.128.2. Administrators should review the GitHub Security Advisory GHSA-q2xx-6h9x-43fw for fix details and apply the upgrade across all deployments.
Workarounds
- Apply an upstream rate limit (for example, at the reverse proxy or API gateway) restricting requests to POST /app/demo per authenticated user.
- Enforce a per-organization quota on the number of demo applications that can exist simultaneously.
- Temporarily disable the /app/demo endpoint for production tenants until the patch is applied.
- Require additional authorization checks or administrative approval before provisioning demo applications.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
