CVE-2025-42602: Meon KYC Auth Bypass Vulnerability

CVE-2025-42602 Overview

CVE-2025-42602 is a session management vulnerability affecting Meon KYC solutions. The flaw stems from improper handling of access and refresh tokens within specific API endpoints used during the authentication process. A remote attacker can intercept and manipulate API response bodies to gain unauthorized access to other user accounts. The vulnerability is classified under [CWE-384: Session Fixation] and was published in the National Vulnerability Database (NVD) on April 23, 2025. CERT-IN tracks this issue as Vulnerability Note CIVN-2025-0082.

Critical Impact
Remote attackers can bypass authentication controls and access arbitrary user accounts by manipulating intercepted API responses containing access and refresh tokens.

Affected Products

Meon KYC solutions (specific versions not enumerated in advisory)
API endpoints involved in authentication workflows
Identity verification and onboarding services built on Meon KYC

Discovery Timeline

2025-04-23 - CVE-2025-42602 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-42602

Vulnerability Analysis

The vulnerability resides in the authentication flow of Meon KYC solutions. Certain API endpoints return access and refresh tokens without sufficient binding to the authenticated user identity. An attacker positioned to intercept HTTP traffic can manipulate the response body containing these tokens. The application accepts the modified tokens during subsequent requests, granting access to accounts belonging to other users. This represents a broken session management implementation classified under [CWE-384].

Root Cause

The root cause lies in the lack of cryptographic binding between session tokens and the requesting client. Access and refresh tokens are returned in API responses without integrity validation. The server-side authentication logic does not verify that tokens presented in subsequent requests originated from the legitimate authentication exchange. This permits token substitution attacks against the authentication boundary.

Attack Vector

The attack requires network-adjacent positioning to intercept API authentication traffic. An attacker captures a target user's authentication response and substitutes token values, or replays harvested tokens through manipulated API request bodies. The attack complexity is elevated because successful exploitation requires the attacker to obtain or influence valid tokens. No user interaction or prior privileges are required. Refer to the CERT-IN Vulnerability Note CIVN-2025-0082 for additional technical context.

Detection Methods for CVE-2025-42602

Indicators of Compromise

Authentication API responses with anomalous token structures or unexpected token lifetimes
Multiple successful authentications for the same user account from disparate IP addresses within short intervals
Refresh token usage patterns that do not align with the original access token issuance
Unexpected account access events following authentication API calls from proxy or interception infrastructure

Detection Strategies

Monitor authentication API endpoints for response body modifications between server emission and client receipt
Correlate token issuance events with subsequent API usage to identify mismatched session contexts
Inspect TLS termination points and reverse proxies for unauthorized response inspection or alteration
Alert on refresh token usage from IP addresses or device fingerprints that differ from the issuing session

Monitoring Recommendations

Enable verbose authentication logging across all Meon KYC API endpoints with full request and response metadata
Forward authentication telemetry to a centralized SIEM for correlation and anomaly detection
Establish baselines for legitimate token refresh cadence and flag deviations
Review user account access logs for activity inconsistent with the account owner's typical patterns

How to Mitigate CVE-2025-42602

Immediate Actions Required

Contact Meon for an official patch or remediation guidance and apply updates as soon as they become available
Invalidate active access and refresh tokens issued prior to remediation and force re-authentication for all users
Enforce HTTPS with strict transport security headers across every API endpoint to reduce interception risk
Audit account activity logs for the period following April 23, 2025 to identify potentially compromised accounts

Patch Information

At the time of publication, no vendor patch URL is listed in the NVD entry for CVE-2025-42602. Organizations operating Meon KYC solutions should engage the vendor directly and reference CERT-IN Vulnerability Note CIVN-2025-0082 for current remediation status.

Workarounds

Implement certificate pinning on client applications to reduce the feasibility of response interception
Bind session tokens to client identifiers such as device fingerprints or IP context where feasible
Reduce access token lifetimes and require additional verification for sensitive account operations
Restrict network paths between clients and Meon KYC APIs to trusted infrastructure and block known proxy interception points

bash

# Example: enforce HSTS and disable token caching at the reverse proxy layer
add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;
add_header Cache-Control "no-store, no-cache, must-revalidate" always;
add_header Pragma "no-cache" always;