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Devolutions ServerApplication · Devolutions

CVE-2026-3204

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-03
Fix available
A fix is available. Upgrade to after 2025.3.16.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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
Improper input validation in the error message page in Devolutions Server 2025.3.16 and earlier allows remote attackers to spoof the displayed error message via a specially crafted URL.

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 · moderate confidence

Improper input validation in Devolutions Server's error message page allows remote attackers to inject malicious content via specially crafted URLs, enabling error message spoofing. This is a classic input validation vulnerability where user-supplied URL parameters are not properly sanitized before being reflected in error page output.

MitigationUpgrade to Devolutions Server version subsequent to 2025.3.16. Until then, implement URL parameter validation and output encoding on all error page rendering code to neutralize injection attempts.

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
Devolutions ServerApplication
Affected:<= 2025.3.16.0

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. Confirm Devolutions Server installation and version
    Locate the Devolutions Server installation directory and check the version file or use the Server Manager console to view the installed version number.
    Affected if The installed version is 2025.3.16.0 or lower.
  2. Verify web interface is exposed
    Check the server configuration or network settings to determine if the Devolutions Server web portal is accessible over HTTP/HTTPS from network locations.
    Affected if The web interface is externally accessible and the server version is vulnerable.
  3. Identify error page endpoints
    Review the web server configuration or application logs to identify URL patterns that trigger error pages, particularly looking for endpoints that accept user-supplied parameters.
    Affected if Error page endpoints accept URL parameters without validation.
  4. Inspect error handling configuration
    Examine the Devolutions Server configuration files for settings related to custom error pages, error message handling, and URL parameter processing.
    Affected if Error handling is configured to reflect URL parameters in output without sanitization.

You are affected if Devolutions Server version 2025.3.16.0 or lower is installed and its web interface is accessible, allowing attackers to inject malicious content via URL parameters in error page requests.

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 2025.3.16.0
Interim mitigation

Upgrade to Devolutions Server version subsequent to 2025.3.16. Until then, implement URL parameter validation and output encoding on all error page rendering code to neutralize injection attempts.

Recommended fix Moderate confidence

Devolutions Server 2025.3.17.0 or later

  1. 1. Identify the current installed version of Devolutions Server by accessing the administration console or checking the application metadata.
  2. 2. Confirm the current version is 2025.3.16.0 or earlier.
  3. 3. Review the official Devolutions release notes at devolutions.net for version 2025.3.17.0 or later to confirm the security fix for this vulnerability.
  4. 4. Create a complete backup of the Devolutions Server database and configuration files before proceeding with the upgrade.
  5. 5. Download the latest stable version of Devolutions Server (2025.3.17.0 or later) from the official Devolutions download portal.
  6. 6. Follow the official upgrade documentation to apply the update, ensuring all prerequisites are met.
  7. 7. After upgrade completion, verify the error message page functions correctly and that the input validation fix is active.
  8. 8. Test with a crafted URL containing special characters to confirm the vulnerability is remediated and error messages cannot be spoofed.
Caveat Review upgrade documentation for potential configuration or migration requirements between versions; minor version upgrades typically have minimal breaking changes

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

Fix this in Devolutions Server Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2026-3204 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