CVE-2025-59826 Overview
CVE-2025-59826 is a missing authorization vulnerability [CWE-862] in Flag Forge, an open-source Capture The Flag (CTF) platform. In version 2.1.0, the platform fails to enforce administrative role checks on the challenge creation endpoint. Authenticated non-admin users can create arbitrary challenges, injecting malicious, incorrect, or misleading content into the platform. The maintainers patched the issue in version 2.2.0.
Critical Impact
Any authenticated user can create CTF challenges intended for administrator-only use, undermining content integrity and enabling distribution of attacker-controlled material to other platform users.
Affected Products
- Flag Forge 2.1.0
- FlagForgeCTF/flagForge repository builds prior to 2.2.0
- Deployments tracking the flagforge:flagforge component
Discovery Timeline
- 2025-09-23 - CVE-2025-59826 published to NVD
- 2025-10-08 - Last updated in NVD database
Technical Details for CVE-2025-59826
Vulnerability Analysis
The vulnerability arises from a broken access control check on the challenge creation API in Flag Forge 2.1.0. The platform exposes challenge creation as a privileged action that should be restricted to administrators. The server-side handler authenticates the user session but does not verify that the caller holds the administrator role before persisting the new challenge.
This is a textbook Missing Authorization weakness [CWE-862]. The application relies on client-side restrictions or insufficient role enforcement, allowing any authenticated participant to invoke the privileged endpoint directly. Successful exploitation lets a low-privileged user inject arbitrary challenge titles, descriptions, flags, hints, and scoring values into the live CTF instance.
Root Cause
The root cause is the absence of a server-side role check on the challenge creation route. Authorization logic that should compare the requesting user's role against an admin requirement is missing or incorrectly applied. The fix in version 2.2.0 introduces the required authorization enforcement on the affected handler.
Attack Vector
The attack vector is network-based and requires only standard user privileges with no user interaction. An attacker registers or signs in as a normal participant, then issues a crafted HTTP request to the challenge creation endpoint. The server accepts the request and stores the attacker-supplied challenge, which is then served to other platform users. Beyond content integrity damage, attackers can use embedded fields to host phishing links, misleading flags, or scripted content that propagates further abuse within the platform.
No public exploit code or proof-of-concept has been published, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. See the GitHub Security Advisory GHSA-q7pg-qchv-3pc5 for vendor details.
Detection Methods for CVE-2025-59826
Indicators of Compromise
- Challenge records in the Flag Forge database whose createdBy or owning user field references a non-administrator account.
- Unexpected spikes in challenge creation events outside scheduled CTF authoring windows.
- Challenge content containing external URLs, unexpected scripts, or references inconsistent with curated event material.
Detection Strategies
- Review application logs for POST requests to the challenge creation endpoint correlated with non-admin session tokens.
- Audit the challenges table to confirm every record maps to an account with the administrator role at creation time.
- Compare the deployed Flag Forge version against 2.2.0 using package manifests or container image tags.
Monitoring Recommendations
- Forward Flag Forge web server and application logs to a centralized log platform with alerting on privileged route access by non-admin roles.
- Enable database audit logging on the challenges table to capture insert events and the associated user identity.
- Track outbound requests originating from rendered challenge content to detect attacker-controlled callback infrastructure.
How to Mitigate CVE-2025-59826
Immediate Actions Required
- Upgrade Flag Forge to version 2.2.0 or later, which contains the authorization fix.
- Inventory existing challenges and remove or quarantine any created by non-administrator accounts in version 2.1.0.
- Rotate any flags or secrets that may have been exposed through unauthorized challenge content.
Patch Information
The maintainers released the fix in Flag Forge 2.2.0. Patch details and vendor guidance are available in the FlagForgeCTF security advisory GHSA-q7pg-qchv-3pc5.
Workarounds
- Restrict network access to the Flag Forge instance to trusted participants and an authenticated reverse proxy until the upgrade is complete.
- Apply a temporary web application firewall rule blocking POST requests to the challenge creation route unless the session belongs to a known administrator account.
- Disable self-service user registration during events so only vetted accounts can reach authenticated endpoints.
# Upgrade Flag Forge to the patched release
git fetch --tags
git checkout v2.2.0
npm ci
npm run build
npm start
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
