CVE-2026-55518 in Avo
Summary
by MITRE • 07/18/2026
Avo is a framework to create admin panels for Ruby on Rails apps. Prior to 3.32.1 and 4.0.0.beta.51, Avo's association attach workflow checks attach_<association>? in the UI and GET /resources/:resource/:id/:related/new path, but the actual write endpoint, POST /resources/:resource/:id/:related, does not run the same authorization check before mutating the association through Avo::AssociationsController#create. An authenticated low-privileged Avo user can bypass hidden or disabled attach controls and directly attach related records to a parent record by sending a crafted POST request, which can lead to privilege escalation and cross-tenant data exposure where associations represent authorization-bearing relationships. This issue is fixed in versions 3.32.1 and 4.0.0.beta.51.
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Analysis
by VulDB Data Team • 07/18/2026
The vulnerability in Avo framework represents a critical authorization bypass flaw that undermines the security controls designed to protect Ruby on Rails admin panel applications. This issue affects versions prior to 3.32.1 and 4.0.0.beta.51, where the framework's association attachment workflow demonstrates inconsistent access control enforcement between read and write operations. The vulnerability stems from a fundamental mismatch in how Avo handles authorization checks during different phases of the association attachment process, creating an exploitable gap that allows malicious actors to circumvent intended security boundaries.
The technical flaw manifests through the inconsistent application of authorization checks within Avo's associations controller. While the user interface properly validates attach_<association>? permissions and hides or disables attachment controls for low-privileged users, the underlying POST endpoint at /resources/:resource/:id/:related fails to perform the same authorization verification before executing the actual mutation operation. This discrepancy creates a scenario where authenticated users with limited privileges can directly manipulate the association attachment process through crafted HTTP requests, bypassing the front-end access control mechanisms that should prevent such operations.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass serious data exposure risks within multi-tenant environments. When associations represent authorization-bearing relationships, an attacker can exploit this flaw to attach records from unauthorized tenants or contexts to parent resources, potentially leading to cross-tenant data leakage and unauthorized access to sensitive information. The vulnerability essentially allows attackers to manipulate the data model structure in ways that should be restricted by the application's authorization framework, creating opportunities for both privilege escalation and data integrity violations.
This security gap aligns with CWE-639 (Authorization Bypass Through User-Controlled Key) and represents a classic case of insufficient authorization checks during write operations. The vulnerability also maps to ATT&CK technique T1078.004 (Valid Accounts: Cloud Accounts) where attackers can leverage legitimate authenticated sessions to perform unauthorized actions through API endpoints that lack proper access controls. The issue demonstrates poor least privilege enforcement and highlights the importance of implementing consistent authorization checks across all request methods, particularly in frameworks that handle complex relationship management between entities.
The recommended mitigation involves upgrading to Avo versions 3.32.1 or 4.0.0.beta.51 where the authorization check has been properly implemented across both read and write operations. Organizations should also conduct thorough security reviews of their admin panel configurations to ensure that similar inconsistencies do not exist in other parts of their application frameworks. Additionally, implementing proper logging and monitoring around association attachment operations can help detect unauthorized attempts to exploit this vulnerability, while regular security testing of API endpoints should verify that access controls are consistently enforced across all HTTP methods.