CVE-2026-77935: Coze Studio Auth Bypass Vulnerability

CVE-2026-77935 Overview

Coze Studio through version 0.5.1 contains an Insecure Direct Object Reference (IDOR) vulnerability [CWE-639] in workflow.go that enables cross-tenant workflow access. Authenticated users can supply foreign workflowID values paired with their own spaceID to interact with workflows owned by other tenants. The flaw affects the save, update_meta, batch_delete, canvas, test_run, and nodeDebug API routes. Attackers can read, execute, overwrite, or delete workflows that belong to different spaces, breaking the tenant isolation model of the platform.

Critical Impact

Any authenticated Coze Studio user can read, modify, execute, or destroy workflows belonging to other tenants, resulting in confidentiality and integrity loss across the multi-tenant deployment.

Affected Products

• Coze Studio versions up to and including 0.5.1
• The backend/application/workflow/workflow.go component
• Multi-tenant Coze Studio deployments exposing workflow API handlers

Discovery Timeline

• 2026-10-20 - CVE-2026-77935 published to NVD
• 2026-10-20 - Last updated in NVD database

Technical Details for CVE-2026-77935

Vulnerability Analysis

The vulnerability resides in the workflow API handlers within backend/application/workflow/workflow.go. The handlers accept both spaceID and workflowID parameters from the client but fail to verify that the referenced workflow actually belongs to the supplied space. The authorization check validates the caller's membership in the provided spaceID without correlating that space with the ownership of the target workflowID.

Because the server trusts the client-supplied identifier pairing, an authenticated user can substitute another tenant's workflowID while continuing to present their own legitimate spaceID. The affected routes include lifecycle operations (save, update_meta, batch_delete), structural operations (canvas), and execution operations (test_run, nodeDebug). Each route performs its action against the attacker-selected workflow with no ownership enforcement.

Root Cause

The root cause is missing object-level authorization. The handler logic treats the spaceID parameter as the authorization scope while using workflowID as the direct lookup key, without a join query to confirm the workflow belongs to the asserted space. This design pattern matches the IDOR class described by CWE-639: Authorization Bypass Through User-Controlled Key.

Attack Vector

Exploitation requires only a valid authenticated session on the Coze Studio instance. An attacker enumerates or obtains a target workflowID from another tenant, then issues a standard API request to any affected route with their own spaceID and the foreign workflowID. The server returns workflow contents, executes the workflow, or applies the requested mutation. No elevated privileges, no user interaction, and no network adjacency beyond normal API reachability are required. Technical details are published in the VulnCheck Advisory for Coze Studio and the Lasso Security CVE-2026-77935 entry. The vulnerable code path is visible in the GitHub Source Code Reference.

Detection Methods for CVE-2026-77935

Indicators of Compromise

• API requests to /workflow/save, /workflow/update_meta, /workflow/batch_delete, /workflow/canvas, /workflow/test_run, or /workflow/nodeDebug where the submitted workflowID does not belong to the submitted spaceID.
• Unexpected modifications, deletions, or executions of workflows attributed to users who are not members of the owning space.
• Spikes in cross-tenant 2xx responses from workflow handlers in access logs.

Detection Strategies

• Correlate spaceID and workflowID in application access logs against the database-recorded owner space for each workflow; flag mismatches.
• Audit the workflow database table for recent updated_at or deletion events performed by principals outside the owning tenant.
• Deploy runtime application monitoring to alert on anomalous workflow enumeration patterns from a single authenticated session.

Monitoring Recommendations

• Enable verbose request logging on all backend/application/workflow endpoints and retain the spaceID, workflowID, and userID fields.
• Baseline per-user workflow API call volumes and alert on sudden increases in unique workflowID references.
• Forward Coze Studio application logs to a centralized analytics platform for cross-tenant anomaly queries.

How to Mitigate CVE-2026-77935

Immediate Actions Required

• Restrict access to Coze Studio to trusted authenticated users until a fixed release is deployed.
• Review recent workflow modifications and deletions across all tenants for evidence of cross-space activity.
• Rotate any secrets, API keys, or credentials embedded in workflows that may have been exposed through unauthorized reads.

Patch Information

At the time of publication, the NVD entry does not list a fixed version. Monitor the Coze Studio GitHub repository and the VulnCheck advisory for an upstream patch that enforces ownership checks binding workflowID to the authenticated user's spaceID.

Workarounds

• Place Coze Studio behind an authenticating reverse proxy that enforces per-tenant allow lists on workflow API routes.
• Apply a middleware shim that resolves the owning spaceID for every submitted workflowID and rejects requests where the values do not match.
• Isolate tenants into separate Coze Studio deployments so that cross-tenant identifier guessing is not reachable.

# Example reverse-proxy guard: reject workflow API calls whose workflowID
# does not resolve to the caller's authorized spaceID.
# Implement in your API gateway or middleware; this is pseudocode.
if resolve_owner_space(request.workflow_id) != session.space_id:
    return 403 "cross-space workflow access denied"