CVE-2025-4129: PAVO Pay Auth Bypass Vulnerability

CVE-2025-4129 Overview

CVE-2025-4129 is an Authorization Bypass Through User-Controlled Key vulnerability affecting PAVO Inc.'s PAVO Pay platform. The flaw allows attackers to exploit trusted identifiers to access resources belonging to other users. The issue is classified under CWE-639 (Authorization Bypass Through User-Controlled Key), commonly known as Insecure Direct Object Reference (IDOR). The vulnerability affects all PAVO Pay versions released before 13.05.2025. Remote attackers can exploit this flaw over the network without authentication or user interaction.

Critical Impact

Unauthenticated remote attackers can manipulate user-controlled identifiers to access confidential data belonging to other PAVO Pay users.

Affected Products

• PAVO Pay versions released before 13.05.2025
• PAVO Inc. payment processing services relying on the vulnerable identifier scheme
• Integrations and merchant deployments using affected PAVO Pay endpoints

Discovery Timeline

• 2025-07-21 - CVE-2025-4129 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-4129

Vulnerability Analysis

The vulnerability resides in PAVO Pay's authorization logic, where the application trusts identifiers supplied by the client to determine resource access. An attacker substitutes another user's identifier in a request and the server returns the targeted user's data without verifying ownership. This pattern, classified as [CWE-639], breaks the authorization model by relying on user-controlled keys instead of server-side session context. The Turkish national CERT, USOM, issued advisory TR-25-0166 to track this issue. Confidentiality of customer payment records, account details, and transactional metadata is at risk. The vulnerability does not require credentials, making automated harvesting of user data feasible at scale.

Root Cause

The root cause is missing or incomplete server-side authorization checks on object references. PAVO Pay endpoints accept identifiers such as user IDs, order numbers, or transaction references and return associated records without validating that the requester owns the resource. Trusted identifiers exposed in URLs, request bodies, or headers become direct attack surfaces.

Attack Vector

An attacker sends crafted HTTP requests to PAVO Pay API endpoints, substituting a target identifier in place of their own. The server processes the request and returns data belonging to the impersonated user. No authentication, privileges, or user interaction are required. Enumeration of sequential or predictable identifiers can expose data across many accounts. Refer to the USOM Security Advisory TR-25-0166 for additional technical context.

Detection Methods for CVE-2025-4129

Indicators of Compromise

• Unusual sequential or enumerated identifier values in API request logs targeting PAVO Pay endpoints
• High request volume from a single source iterating through user, order, or transaction IDs
• Responses containing data for identifiers not associated with the authenticated session
• Requests to PAVO Pay endpoints from IP addresses outside expected merchant or customer geographies

Detection Strategies

• Inspect application logs for repeated 200 OK responses tied to varying identifier parameters from one client
• Correlate session identity with returned resource ownership at the API gateway layer
• Deploy anomaly detection on identifier access patterns, flagging rapid enumeration sequences
• Compare access requests against expected user-to-resource mappings to surface cross-account reads

Monitoring Recommendations

• Forward PAVO Pay API access logs to a centralized analytics platform for continuous review
• Alert on spikes in unique identifier values requested per session within short time windows
• Track outbound data volumes from PAVO Pay endpoints to detect bulk extraction attempts
• Review authentication and authorization decisions for any endpoint exposing user-keyed objects

How to Mitigate CVE-2025-4129

Immediate Actions Required

• Upgrade PAVO Pay to the version released on or after 13.05.2025
• Audit API endpoints to confirm server-side ownership checks are enforced for every resource access
• Rotate session tokens and review recent access logs for unauthorized cross-account requests
• Notify affected merchants and customers if log review identifies suspected data exposure

Patch Information

PAVO Inc. addressed CVE-2025-4129 in PAVO Pay releases after 13.05.2025. Operators should consult PAVO Inc. directly for upgrade artifacts and verify version metadata after deployment. The USOM Security Advisory TR-25-0166 provides the authoritative reference for the fix and disclosure.

Workarounds

• Place a reverse proxy or API gateway in front of PAVO Pay to enforce per-session authorization checks until patching completes
• Replace predictable identifiers with unguessable values such as UUIDs to slow enumeration attempts
• Apply rate limiting on endpoints that return user-keyed objects to constrain bulk access attempts
• Restrict access to administrative and customer endpoints by IP allowlist where business workflows allow

# Configuration example
# See PAVO Inc. official upgrade documentation and USOM advisory TR-25-0166 for vendor-supplied remediation steps.