CVE-2026-62235: Grav Flex-Objects Auth Bypass Vulnerability

CVE-2026-62235 Overview

CVE-2026-62235 is a broken access control vulnerability in the Grav Flex-Objects plugin before version 1.4.3. The flaw resides in the admin-next REST API, which fails to enforce authorization on directories that lack an explicit permissions configuration. Authenticated users holding only the api.access permission can perform unauthorized create, read, update, delete, and export (CRUD) operations against these permission-less directories. The vulnerability is classified under CWE-636: Not Failing Securely (Failing Open).

Critical Impact
Authenticated attackers with minimal api.access credentials can bypass intended authorization controls and manipulate content in any Flex-Objects directory lacking explicit permissions configuration.

Affected Products

Grav CMS Flex-Objects plugin versions prior to 1.4.3
Grav installations using the admin-next REST API
Any Grav directory that does not define explicit permissions configuration

Discovery Timeline

2026-07-17 - CVE-2026-62235 published to NVD
2026-07-17 - Last updated in NVD database

Technical Details for CVE-2026-62235

Vulnerability Analysis

The Grav Flex-Objects plugin exposes a REST API under the admin-next route to manage structured content directories. The plugin's authorization model expects each directory to define an explicit permissions configuration that governs which capabilities apply to which operations. When a directory omits this configuration, the API fails open rather than denying access by default.

As a result, any authenticated principal holding the api.access permission can invoke CRUD and export handlers against directories that were never intended to be publicly writable. The api.access permission was designed as a coarse-grained gate for API entry, not as a substitute for per-directory authorization. This design assumption breaks in the presence of directories that ship without explicit permissions blocks.

Root Cause

The root cause is a failure to fail securely [CWE-636]. The authorization layer treats a missing permissions configuration as permissive rather than restrictive. Rather than denying operations on directories without an explicit policy, the plugin allows any api.access holder to proceed. This inverts the principle of least privilege and produces silent authorization bypass across every unconfigured directory.

Attack Vector

Exploitation requires network access to the Grav admin API and valid credentials with the api.access permission. An attacker authenticates to the admin-next REST endpoint and issues standard CRUD or export requests against a target directory that lacks explicit permissions configuration. The server processes the request without evaluating whether the caller has directory-level rights. See the GitHub Security Advisory GHSA-23vq-365v-qcmh and the VulnCheck Authorization Bypass Advisory for reference details.

No verified proof-of-concept code is publicly available. The vulnerability is exercised through legitimate API call patterns rather than malformed input, which reduces the signal available to signature-based detection.

Detection Methods for CVE-2026-62235

Indicators of Compromise

Unexpected write, update, or delete requests to admin-next REST API endpoints from accounts with only api.access permission.
Export operations invoked against Flex-Objects directories that do not contain explicit permissions definitions.
Content modifications in Flex-Objects directories with no corresponding change in the admin UI audit trail.

Detection Strategies

Audit Flex-Objects directory configurations for missing permissions blocks and correlate against API access logs.
Baseline expected API callers per directory and alert on api.access-only principals invoking CRUD verbs.
Review web server logs for HTTP POST, PUT, PATCH, and DELETE requests to /admin-next/ routes and validate against the caller's assigned roles.

Monitoring Recommendations

Enable verbose logging on the Grav admin API and forward events to a centralized log platform for correlation.
Monitor changes to files under the user/data/flex-objects/ and related content directories outside expected editorial workflows.
Track creation of new API tokens and any elevation of accounts to the api.access capability.

How to Mitigate CVE-2026-62235

Immediate Actions Required

Upgrade the Grav Flex-Objects plugin to version 1.4.3 or later on all instances.
Inventory every Flex-Objects directory and add an explicit permissions configuration to each one.
Review and revoke api.access permission from accounts that do not require programmatic API use.

Patch Information

Grav Flex-Objects version 1.4.3 addresses CVE-2026-62235 by enforcing default-deny behavior when a directory lacks an explicit permissions configuration. Administrators should apply the upgrade through the standard Grav plugin manager and validate the version post-deployment. Full remediation guidance is available in the GitHub Security Advisory GHSA-23vq-365v-qcmh.

Workarounds

Add an explicit permissions: block to every Flex-Objects directory blueprint until the patch can be deployed.
Restrict access to the admin-next API at the reverse proxy or web application firewall level to trusted source addresses.
Rotate credentials and API tokens for accounts that previously held the api.access permission.

bash

# Configuration example: enforce explicit directory permissions in blueprint YAML
# user/blueprints/flex-objects/<directory>.yaml
config:
  admin:
    permissions:
      admin.super: create,read,update,delete,list
      admin.<directory>: create,read,update,delete,list