CVE-2026-56255: Capgo Denial of Service via Unthrottled Demo Application Creation

Technical summary

The vulnerability exists in the POST /app/demo endpoint of Capgo prior to version 12.128.2. The endpoint fails to enforce rate limits or creation quotas on demo application generation. An authenticated attacker with org write permissions can invoke this endpoint repeatedly, triggering ~138 database write operations per request (CWE-770: Allocation of Resources Without Limits or Throttling). This resource exhaustion can cause cascading performance degradation and increased infrastructure costs.

Business impact

This vulnerability enables a disruptive attack from insider threats or compromised accounts with org write permissions. Repeated abuse degrades platform responsiveness for legitimate users, increases cloud database and compute costs without corresponding legitimate activity, and risks service unavailability during peak exploitation. Organizations relying on Capgo for continuous deployment may face interrupted workflows and customer-facing incidents.

Affected systems

Capgo deployments running versions prior to 12.128.2 are affected. The vulnerability requires the attacker to possess valid authentication credentials and org write permissions, limiting exposure to authorized users or those with stolen credentials. Any organization using Capgo in a multi-tenant or shared environment should treat this as an elevated insider risk.

Exploitability

Exploitability is moderate. The attack requires valid authentication and org write permissions—not trivial prerequisites. However, the attack itself is trivial to execute once credentials are obtained: simple HTTP POST requests to a known endpoint with no additional obfuscation needed. There is no CVSS environmental or temporal adjustment in the data, but operationally this is more dangerous in environments with weak credential hygiene or excessive permission delegation.

Remediation

Upgrade Capgo to version 12.128.2 or later. This patch should include rate limiting and quota enforcement on the POST /app/demo endpoint. After patching, conduct a retroactive audit of demo application creation logs to detect any suspicious spike in creation activity from user accounts, which could indicate exploitation during the window of vulnerability.

Patch guidance

Apply Capgo version 12.128.2 or newer as soon as feasible. Prioritize this in environments where org write permissions are widely held or where user accounts have administrative scope. Test the patch in a staging environment to confirm that legitimate demo application workflows are not disrupted by newly enforced rate limits. Coordinate the upgrade during a maintenance window to avoid sudden service disruptions.

Detection guidance

Monitor POST /app/demo endpoint activity for abnormal request volumes from individual users or service accounts. Baseline normal demo application creation rates and alert on sustained spikes—e.g., >10 requests per minute per user, or bulk creation by accounts that do not typically create demos. Cross-correlate with database load metrics; exploitation will cause a marked increase in write operations without corresponding legitimate application traffic. Review access logs and API audit trails for any accounts with org write permissions that have been recently created or delegated unusual scope.

Why prioritize this

This is a MEDIUM severity vulnerability suitable for standard patch cycles, not emergency response. However, prioritization should increase if your organization has (1) loose permission delegation (many users with org write permissions), (2) a history of insider threats or account compromise, or (3) cost-sensitive cloud infrastructure where resource exhaustion directly impacts budget. The lack of CVE-2026-56255 in CISA's KEV catalog suggests low active exploitation in the wild to date.

Risk score, explained

CVSS 3.1 score of 4.3 (MEDIUM) reflects the limited impact scope: authentication and org write permissions are required (PR:L), no confidentiality or integrity loss (C:N/I:N), only availability degradation (A:L), and the attack requires no user interaction (UI:N) over a network vector (AV:N/AC:L/S:U). The score appropriately de-prioritizes this below critical or high-severity flaws, but the operational and financial impact should be evaluated independently of the base score in your risk model.

Frequently asked questions