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Firewall CommunityApplication · Endian

CVE-2026-34821

MEDIUM · 5.4 CVSS v3.1 Published 2026-04-02
Fix available
A fix is available. Upgrade to after 3.3.25 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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
Endian Firewall version 3.3.25 and prior allow stored cross-site scripting (XSS) via the remark parameter to /manage/vpnauthentication/user/. An authenticated attacker can inject arbitrary JavaScript that is stored and executed when other users view the affected page.

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

Endian Firewall versions 3.3.25 and prior contain a stored cross-site scripting vulnerability in the VPN authentication user management interface (/manage/vpnauthentication/user/). An authenticated attacker can inject malicious JavaScript through the 'remark' parameter, which persists and executes in the browsers of other users viewing the affected page.

MitigationImplement proper input validation and sanitization on the remark parameter, combined with output encoding when rendering user-supplied data to prevent script execution.

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
Firewall CommunityApplication
Affected:<= 3.3.25

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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

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 Endian Firewall version
    Access the web administration console and navigate to the System > Status or Dashboard section to view the installed version number. Alternatively, check the version via CLI using 'cat /etc/redhat-release' or 'Endian--version' if available.
    Affected if The installed version is 3.3.25 or any prior version (e.g., 3.3.24, 3.3.20, etc.).
  2. Verify VPN authentication module is accessible
    Log into the Endian Firewall web interface and navigate to the VPN section. Confirm whether the 'VPN authentication' or 'User Management' submenu exists under the VPN configuration area.
    Affected if The VPN authentication user management interface at /manage/vpnauthentication/user/ is present and accessible within the administration panel.
  3. Inspect VPN user accounts for stored XSS payloads
    Access the VPN authentication user management page (/manage/vpnauthentication/user/) and review all user entries. Examine the 'remark' or 'notes' field for each user account for any unexpected characters, HTML tags, or script elements.
    Affected if Any user account in the VPN authentication list displays unsanitized HTML, JavaScript tags, or unexpected content in the remark/notes field that could execute in a browser.
  4. Check for unauthorized or suspicious VPN user accounts
    Review the list of VPN authentication users for accounts you did not create. Look for accounts with unusual names, generic patterns, or accounts added by other administrators without prior notification.
    Affected if Unexpected VPN user accounts exist that were not created by authorized administrators, indicating potential compromise.

You are affected if running Endian Firewall Community version 3.3.25 or earlier and the VPN authentication user management interface is accessible, with any unsanitized content present in the remark field of VPN user accounts.

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 a release after 3.3.25
Interim mitigation

Implement proper input validation and sanitization on the remark parameter, combined with output encoding when rendering user-supplied data to prevent script execution.

Recommended fix Moderate confidence

Latest Endian Firewall Community release (version > 3.3.25)

  1. 1. Identify the current Endian Firewall Community version by accessing the admin interface or checking system information
  2. 2. Navigate to the official Endian download page or contact Endian support to obtain the latest stable release
  3. 3. Before upgrading, backup all critical configurations and data
  4. 4. Perform the upgrade following the official Endian upgrade documentation
  5. 5. After upgrade, verify the XSS vulnerability is resolved by attempting to inject script via the /manage/vpnauthentication/user/ remark parameter (in a test environment)
  6. 6. Confirm all users can access the VPN authentication user management page without issues
Caveat Review Endian release notes for any breaking changes between 3.3.25 and the target version, particularly regarding VPN authentication features

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

Fix this in Firewall Community 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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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-2026-34821 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