What is the CVSS score of CVE-2026-3204?

CVE-2026-3204 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

How to fix or mitigate CVE-2026-3204?

Within 24 hours: Inventory all Devolutions Server instances and confirm versions running 2025.3.16 or earlier; notify security teams and prepare incident response procedures. Within 7 days: Implement WAF rules to detect and block malicious URL patterns targeting error pages; restrict direct internet access to Devolutions Server where possible through network segmentation. Within 30 days: Contact Devolutions for patch availability and emergency updates; test patches in non-production environments and deploy to all affected systems on an expedited schedule.

Devolutions Server CVE-2026-3204

CRITICAL

Improper Input Validation (CWE-20)

2026-03-03 security@devolutions.net

Code Injection Devolutions Server Devolutions

9.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft malicious URL with injected parameters
Exploit

Send URL to target user
Execution

Error page renders unsanitized input
Impact

Display spoofed error message to victim

Vulnerability Assessment

Weakness	CWE CWE-20 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V2 - Validation and Business Logic Input validation, allowlisting
Exploitation Conditions	Devolutions Server 2025.3.16 or earlier with error message page accessible via HTTP/HTTPS. No authentication required. Victim must visit attacker-controlled or attacker-modified URL.
Impact	CVSS 9.8.
Exploit ScenarioDerived	Spoof error messages for phishing.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Input validation flaw in Devolutions Server error message page enables remote spoofing attacks.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:05 CVSS 9.8

Error page spoofing in Devolutions Server.

RemediationAI

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Technical ContextAI · show details

CWE-20.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

CVE-2026-3204 is a critical vulnerability affecting Devolutions Server 2025.3.16 and earlier that allows attackers to spoof error messages through specially crafted URLs. While the immediate technical impact appears limited to display manipulation, this vulnerability could be leveraged in sophisticated phishing campaigns targeting your organization's users, potentially compromising credentials and sensitive information.

Business Impact: High

Compensating Controls

Implement Web Application Firewall (WAF) rules to detect and block crafted URLs exploiting error message parameters; restrict network access to Devolutions Server using firewall rules limiting connections to authorized IP ranges only; disable public-facing error message pages if functionality permits; implement user awareness training on phishing indicators; enable multi-factor authentication to mitigate credential compromise from spoofed messages; monitor for anomalous URL patterns in server logs; consider isolating affected Devolutions instances until patch is available.

Threat Intelligence Overview

EPSS Score

0.1%

Top 79% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.1%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +49

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.