CVE-2025-29996: CAP Back Office 2FA Bypass Vulnerability

CVE-2025-29996 Overview

CVE-2025-29996 is an authentication bypass vulnerability in the CAP back office application. The flaw resides in the API-based login flow, where the One-Time Password (OTP) verification mechanism is improperly implemented. A remote attacker holding valid credentials can manipulate the API request URL or payload to bypass Two-Factor Authentication (2FA) for other user accounts. The issue is tracked under [CWE-288: Authentication Bypass Using an Alternate Path or Channel] and was published to the NVD on March 13, 2025. CERT-In assigned vulnerability note CIVN-2025-0048 for tracking and coordinated disclosure.

Critical Impact

An authenticated attacker can bypass the OTP step of 2FA and gain access to other users' accounts through manipulated API requests, leading to account takeover within the CAP back office.

Affected Products

• CAP back office application (API-based login component)
• Deployments relying on the affected OTP verification flow for 2FA enforcement
• Refer to CERT-In Vulnerability Note CIVN-2025-0048 for specific version coverage

Discovery Timeline

• 2025-03-13 - CVE-2025-29996 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-29996

Vulnerability Analysis

The vulnerability stems from improper enforcement of the OTP verification step within the CAP back office API authentication workflow. After the first authentication factor succeeds, the server-side logic fails to bind the OTP challenge to the originating user session or account identifier. An attacker who already holds valid credentials can craft API requests that reference a different user account during the OTP verification phase. The server accepts the manipulated request, treating the OTP challenge as satisfied for the targeted account. This breaks the security guarantee of 2FA, as possession of the second factor for the victim account is not actually verified.

Root Cause

The root cause is a logic flaw in the API login handler. The OTP verification endpoint relies on client-supplied parameters in the request URL or JSON payload to determine which account is being authenticated. Because the server does not cryptographically tie the OTP challenge to a specific session and account on the back end, attackers can substitute account identifiers. This pattern aligns with [CWE-288], where an alternate authentication path lacks the controls present on the primary path.

Attack Vector

Exploitation requires network access to the CAP back office API and a set of valid credentials for any account. The attacker initiates the login flow, intercepts the API request issued during the OTP step using a proxy such as Burp Suite, and modifies the user identifier or session reference to point at a different account. The server completes the login as the targeted user without validating possession of that user's OTP. No user interaction from the victim is required, and exploitation can be scripted against enumerated account identifiers.

No public proof-of-concept exploit code is available. Technical specifics are restricted in the CERT-In Vulnerability Note CIVN-2025-0048.

Detection Methods for CVE-2025-29996

Indicators of Compromise

• Successful logins where the user identifier in the OTP verification request differs from the account that initiated the credential submission
• API authentication sequences where the OTP step completes without a preceding OTP delivery event for the same account
• Multiple successful logins to distinct accounts originating from the same client IP, user agent, or session token within a short window
• Anomalous session creation events for privileged back office accounts outside normal business hours

Detection Strategies

• Correlate OTP issuance logs with OTP verification logs and alert on mismatched account identifiers between the two events
• Instrument the API gateway to log full request paths and payloads for /login and /verify-otp endpoints, then baseline normal parameter values per session
• Apply behavioral analytics to flag accounts that authenticate from new IP addresses immediately after another account's failed or partial login

Monitoring Recommendations

• Forward CAP back office application logs, API gateway logs, and authentication server logs to a centralized SIEM for cross-source correlation
• Enable alerting on bulk account access patterns and rapid switching between user contexts from a single source
• Review privileged account sessions daily until the vendor patch is applied and verified

How to Mitigate CVE-2025-29996

Immediate Actions Required

• Restrict network access to the CAP back office API to trusted management networks or VPN-only access until a fix is deployed
• Force a password reset and re-enrollment of 2FA tokens for all back office users, prioritizing administrative accounts
• Review authentication logs since March 2025 for signs of OTP bypass and account takeover
• Engage the vendor and reference CERT-In Vulnerability Note CIVN-2025-0048 to obtain the official patch or hotfix

Patch Information

No vendor patch URL is published in the NVD record at the time of writing. Administrators should contact the CAP back office vendor directly and monitor the CERT-In advisory for updated remediation guidance. Apply the fixed build as soon as it becomes available and validate that the OTP verification endpoint enforces server-side binding between the credential submission and the OTP challenge.

Workarounds

• Disable API-based login paths if a web-based login flow with enforced OTP binding is available
• Enforce IP allow-listing on the authentication API to limit exposure to known administrator networks
• Add a reverse proxy or WAF rule that rejects OTP verification requests where the account identifier in the payload does not match the account associated with the active session token
• Increase logging verbosity on the authentication API and review logs for the indicators listed above

# Example WAF rule concept (vendor-neutral pseudocode) to block
# OTP verification requests with mismatched account identifiers.
# Replace endpoint paths and field names with values from your deployment.

SecRule REQUEST_URI "@beginsWith /api/login/verify-otp" \
  "phase:2,deny,status:403,log,\
   msg:'CVE-2025-29996: OTP account mismatch',\
   chain"
  SecRule ARGS:user_id "!@streq %{SESSION.user_id}"