CVE-2026-58448: yudao-cloud BPM Broken Access Control Vulnerability – Patch Guidance

Technical summary

CVE-2026-58448 is a broken access control vulnerability (CWE-862) in yudao-cloud's BPM module stemming from missing @PreAuthorize authorization checks on a GET endpoint. The endpoint accepts a caller-supplied process-instance identifier without validating ownership or tenant affiliation. Attackers can enumerate or directly request arbitrary process-instance IDs to retrieve sensitive attributes including form variables, approver identities, approval/rejection comments, and BPMN XML definitions. The vulnerability requires prior authentication but no elevated privileges, enabling horizontal privilege escalation across process instances and tenants.

Business impact

This vulnerability exposes confidential business workflows and decision-making information to unauthorized internal or contracted users. Process approvals, rejections, and associated comments may leak competitive strategy, personnel decisions, or sensitive project details. Multi-tenant deployments face cross-tenant data leakage risk. Compliance frameworks (GDPR, HIPAA, SOC 2) that govern workflow data access may be violated, triggering audit findings and potential regulatory penalties. Insider threats become more feasible when workflow history and approver identities are freely readable.

Affected systems

yudao-cloud versions prior to 2026.06 are affected. The BPM module is the attack surface; all instances with the module enabled and at least one authenticated user are at risk. Multi-tenant deployments are particularly vulnerable because tenant isolation is not enforced at the endpoint level.

Exploitability

Exploitation requires valid login credentials (low barrier for internal users, contractors, or compromised accounts) and network access to the BPM module endpoint. No special tools, user interaction, or complex exploitation steps are needed—attackers can use standard HTTP clients to iterate through process-instance IDs. The unprotected endpoint is discoverable through normal API enumeration. CVSS 6.5 (Medium) reflects the requirement for prior authentication offset by high confidentiality impact and ease of exploitation once authenticated.

Remediation

Upgrade yudao-cloud to version 2026.06 or later. The patch adds @PreAuthorize annotations and ownership/tenant verification logic to the vulnerable endpoint. Organizations unable to patch immediately should restrict network access to the BPM module endpoints using firewalls or API gateways, implement additional logging on process-instance queries for anomaly detection, and review access logs for suspicious enumeration patterns.

Patch guidance

Apply the yudao-cloud 2026.06 release. Verify compatibility with your current deployment configuration before rolling out to production. If running a multi-tenant instance, confirm that the patch enforces tenant isolation across all BPM endpoints. Test process retrieval workflows post-patch to ensure legitimate access is not disrupted. Consider a staged rollout to detect edge cases.

Detection guidance

Monitor logs for repeated GET requests to BPM process-instance endpoints with varying or sequential process-instance IDs from the same user or IP address—a sign of enumeration. Flag requests to process instances the user should not have access to based on ownership records or tenant assignment. Implement alerting on unauthorized access attempts if the application logs authorization failures. In network-level detection, watch for unusual query patterns to the endpoint (e.g., high request volume, diverse parameter values).

Why prioritize this

Although CVSS 6.5 classifies this as Medium, it merits priority consideration because (1) it enables horizontal privilege escalation across workflow records with minimal effort, (2) authenticated user bases often include contractors and third parties with broad access, (3) multi-tenant SaaS deployments can suffer cross-organization data leakage, and (4) workflow data frequently contains compliance-sensitive information. Organizations with strong insider-threat concerns or strict data-segregation requirements should prioritize patching.

Risk score, explained

CVSS 3.1 score of 6.5 reflects: Attack Vector (Network), Attack Complexity (Low), and Privileges Required (Low) yield a base of 6.5. Confidentiality Impact (High) drives the score upward because attackers gain read access to sensitive form data and process definitions. Integrity and Availability are unaffected (None). The score does not account for business context (e.g., presence of PII, multi-tenancy, regulatory obligations), which may warrant local score adjustments in enterprise risk frameworks.

Frequently asked questions