Executive Summary

CVE-2026-56216 is a privilege escalation vulnerability in Capgo versions before 12.128.2. It occurs in the POST /functions/v1/apikey endpoint, where app-limited API keys can create unrestricted API keys by setting empty limits. This happens because the system only blocks key creation for keys limited to organizations but does not properly restrict keys limited to specific apps. An attacker who has compromised an app-limited key can exploit this flaw to mint a fully unrestricted key that grants organization-wide access to resources.

The unrestricted key can access sensitive endpoints such as app listings and other protected resources, bypassing intended least-privilege controls. The root cause is improper authorization checks related to privilege management.

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Impact Analysis

If an attacker compromises an app-limited API key, they can exploit this vulnerability to create an unrestricted API key with organization-wide access. This allows the attacker to access sensitive resources such as app listings and other protected endpoints that should normally be restricted.

This escalation of privileges can lead to unauthorized data exposure, manipulation of resources, and potentially further attacks within the organization’s environment.

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Detection Guidance

This vulnerability involves the creation of unrestricted API keys from app-limited keys by calling the POST /functions/v1/apikey endpoint with empty limits.

To detect exploitation attempts on your network or system, monitor API calls to the /functions/v1/apikey endpoint, specifically looking for requests where the payload includes empty arrays for both limited_to_apps and limited_to_orgs fields.

Example detection commands might include:

• Using network traffic inspection tools (e.g., tcpdump, Wireshark) to filter HTTP POST requests to /functions/v1/apikey and analyze the JSON payload for empty limits.
• Using log analysis commands such as: grep 'POST /functions/v1/apikey' /path/to/api/logs | grep -E '"limited_to_apps":\[\],"limited_to_orgs":\[\]'
• Implementing API gateway or WAF rules to alert on or block requests with empty limits in the key creation endpoint.

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Mitigation Strategies

Immediate mitigation steps include upgrading Capgo to version 12.128.2 or later, where the vulnerability has been fixed.

If upgrading is not immediately possible, restrict or monitor the use of app-limited API keys to prevent unauthorized creation of unrestricted keys.

Additionally, implement server-side validation to ensure that keys created cannot exceed the scope of the caller, treating keys with either limited_to_orgs or limited_to_apps as limited for key creation purposes.

Review and audit API key usage and creation logs to detect any suspicious activity related to key minting.

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Compliance Impact

This vulnerability allows attackers to escalate privileges by creating unrestricted API keys with organization-wide access, potentially exposing sensitive data and resources that should be protected under least-privilege principles.

Such unauthorized access could lead to violations of data protection regulations like GDPR and HIPAA, which require strict controls on access to personal and sensitive information.

By enabling attackers to bypass intended access restrictions, the vulnerability undermines compliance with these standards that mandate proper authorization and access management.

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