FlagforgeApplication

CVE-2025-59841

CRITICAL · 9.8 CVSS v3.1 Published 2025-09-25
Fix available
A fix is available. Upgrade to 2.3.1 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Flag Forge is a Capture The Flag (CTF) platform. In versions from 2.2.0 to before 2.3.1, the FlagForge web application improperly handles session invalidation. Authenticated users can continue to access protected endpoints, such as /api/profile, even after logging out. CSRF tokens are also still valid post-logout, which can allow unauthorized actions. This issue has been patched in version 2.3.1.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Flag Forge versions 2.2.0 through 2.3.0 contain improper session invalidation where authenticated sessions are not terminated upon logout. Users can continue accessing protected API endpoints such as /api/profile after logging out, and CSRF tokens remain valid post-logout, enabling potential session hijacking or CSRF attacks.

MitigationUpgrade to version 2.3.1 or later. Additionally, implement proper server-side session destruction and CSRF token invalidation on logout, and consider adding session timeout policies.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FlagforgeApplication
Affected:>= 2.2, < 2.3.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Flag Forge version
    Check your application version file or metadata (common locations: package.json, version.txt, about page, or admin dashboard). Compare the version number against the affected range: >= 2.2.0 and < 2.3.1.
    Affected if Version is 2.2.0, 2.2.1, 2.2.2, 2.2.3, 2.2.4, 2.2.5, 2.2.6, 2.2.7, 2.2.8, 2.2.9, 2.3.0 (any version from 2.2.0 through 2.3.0)
  2. Test session persistence after logout
    Log into the application, perform a logout, then attempt to access a protected endpoint such as /api/profile using the same session cookie or token that was used before logout.
    Affected if The request to /api/profile returns successful data or a 200 OK response after logout, indicating the session is still valid
  3. Verify CSRF token invalidation
    After logging out, attempt to perform an action that requires a CSRF token (such as a form submission or API POST request) using the previously issued CSRF token.
    Affected if The action is processed successfully or the server accepts the old CSRF token, indicating tokens remain valid post-logout
  4. Check session storage configuration
    Inspect server-side session storage (database, Redis, file-based sessions) to confirm whether session records are being deleted or marked as invalid upon logout request.
    Affected if Session records persist in storage after logout, or session data is not being destroyed server-side

You are affected if your Flag Forge version is between 2.2.0 and 2.3.0 (inclusive) AND logout does not terminate your session or invalidate CSRF tokens.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.3.1 or later
Fixed in 2.3.1
Vendor patch github.com →
Interim mitigation

Upgrade to version 2.3.1 or later. Additionally, implement proper server-side session destruction and CSRF token invalidation on logout, and consider adding session timeout policies.

Recommended fix High confidence

2.3.1

  1. Check current installed version of FlagForge
  2. Upgrade to version 2.3.1 using the appropriate package manager (e.g., pip install flagforge==2.3.1, npm install, or equivalent)
  3. Restart the FlagForge service if running
  4. Verify the upgrade was successful by checking the version number
  5. Test that session invalidation now works correctly: log in, log out, and confirm protected endpoints like /api/profile return authentication errors
  6. Verify CSRF tokens are invalidated upon logout

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Flagforge Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-59841 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data