CVE-2025-61777: Flagforge Auth Bypass Vulnerability

CVE-2025-61777 Overview

Flag Forge is a Capture The Flag (CTF) platform used for cybersecurity competitions and training. A critical authentication bypass vulnerability was discovered in versions 2.0.0 through 2.3.1, where the /api/admin/badge-templates (GET) and /api/admin/badge-templates/create (POST) endpoints allowed access without any authentication or authorization checks. This flaw could enable unauthorized users to retrieve all badge templates including sensitive metadata such as createdBy, createdAt, and updatedAt fields, as well as create arbitrary badge templates in the database.

Critical Impact

Unauthenticated attackers can access and manipulate badge template data remotely, leading to data exposure, database pollution, and potential abuse of the badge system in CTF competitions.

Affected Products

• FlagForge versions 2.0.0 to 2.3.1
• /api/admin/badge-templates endpoint (GET requests)
• /api/admin/badge-templates/create endpoint (POST requests)

Discovery Timeline

• 2025-10-06 - CVE-2025-61777 published to NVD
• 2025-10-30 - Last updated in NVD database

Technical Details for CVE-2025-61777

Vulnerability Analysis

This vulnerability represents a combination of two critical weakness classes: Missing Authentication for Critical Function (CWE-306) and Information Exposure (CWE-200). The Flag Forge application failed to implement proper authentication and authorization controls on administrative API endpoints responsible for managing badge templates.

The affected endpoints are designed for administrative use and should only be accessible by authenticated administrators. However, due to missing access controls, any user—authenticated or not—could interact with these endpoints. This creates a significant attack surface where sensitive metadata about badge templates, including creation timestamps and user identifiers, could be exfiltrated. Additionally, attackers could inject arbitrary badge templates into the database, potentially disrupting CTF competitions or manipulating the badge reward system.

Root Cause

The root cause of this vulnerability stems from missing authentication middleware on the administrative badge template API routes. The application failed to enforce authentication requirements before processing requests to the /api/admin/badge-templates and /api/admin/badge-templates/create endpoints. Without these security controls, the application processed all incoming requests regardless of the caller's authentication status or role.

Attack Vector

The vulnerability is exploitable over the network without requiring any authentication or user interaction. An attacker can directly send HTTP requests to the vulnerable API endpoints to either retrieve sensitive badge template data or create malicious badge entries.

For retrieving badge templates, an attacker would send a GET request to /api/admin/badge-templates, which would return all badge template records including sensitive metadata fields. For creating arbitrary badge templates, a POST request to /api/admin/badge-templates/create with appropriately formatted JSON payload would insert new records into the database.

The attack requires no special privileges and can be automated to enumerate or pollute the badge template database. See the GitHub Security Advisory for additional technical details.

Detection Methods for CVE-2025-61777

Indicators of Compromise

• Unexpected or unauthorized entries in the badge templates database table
• HTTP access logs showing requests to /api/admin/badge-templates or /api/admin/badge-templates/create from unauthenticated sessions
• Anomalous metadata values (createdBy, createdAt) in badge template records that do not match legitimate administrator activity
• High volume of GET requests to admin endpoints from external IP addresses

Detection Strategies

• Monitor web server access logs for requests to /api/admin/badge-templates* endpoints, particularly from sessions lacking valid authentication tokens
• Implement database audit logging to track INSERT operations on badge template tables and flag records created without corresponding authenticated admin sessions
• Deploy web application firewall (WAF) rules to detect and alert on unauthenticated access attempts to administrative API paths
• Review application logs for missing authentication context on admin endpoint requests

Monitoring Recommendations

• Configure SIEM alerts for any access to /api/admin/ paths without valid session tokens or JWT authentication headers
• Establish baseline metrics for badge template creation frequency and alert on anomalous spikes
• Implement real-time monitoring of database record counts for badge templates to detect mass injection attacks
• Enable API gateway logging with detailed request/response capture for forensic analysis capabilities

How to Mitigate CVE-2025-61777

Immediate Actions Required

• Upgrade FlagForge to version 2.3.2 or later immediately
• Audit existing badge template database entries for unauthorized or suspicious records created during the vulnerability window
• Review web server access logs for evidence of exploitation attempts against the affected endpoints
• Rotate any credentials or tokens that may have been exposed through metadata leakage

Patch Information

The vulnerability has been fixed in FlagForge version 2.3.2. The patch implements authentication requirements on GET, POST, UPDATE, and DELETE operations for badge template endpoints. Additionally, authorization checks now ensure only users with administrator privileges can access and modify badge templates.

For patch details, see the GitHub Commit Reference which addresses the missing authentication controls.

Workarounds

• No reliable workarounds are available according to the vendor advisory
• As a temporary measure, restrict access to the FlagForge application at the network level using firewall rules to limit exposure until patching is completed
• Consider placing a reverse proxy or WAF in front of the application configured to block unauthenticated requests to /api/admin/* endpoints
• If possible, take the affected FlagForge instance offline until the upgrade to version 2.3.2 can be completed

# Upgrade FlagForge to patched version
# Consult FlagForge documentation for your deployment method
# Example for typical Node.js deployment:
git pull origin main
git checkout v2.3.2
npm install
npm run build
# Restart the application service