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Servicestack CVE-2025-6444

| EUVDEUVD-2025-19133 MEDIUM
Improper Input Validation (CWE-20)
2025-06-25 zdi-disclosures@trendmicro.com
5.9
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V2 - Validation and Business Logic Input validation, allowlisting
Impact

CVSS score of 5.9 (MEDIUM).

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 15, 2026

ServiceStack GetErrorResponse Improper Input Validation NTLM Relay Vulnerability. This vulnerability allows remote attackers to relay NTLM credentials on affected installations of ServiceStack. Interaction with this library is required to exploit this vulnerability but attack vectors may vary depending on the implementation.

The specific flaw exists within the implementation of the GetErrorResponse method. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to relay NTLM credentials in the context of the current user. Was ZDI-CAN-25834.

Earlier versions of this analysis (1)
v1 Mar 15, 2026 - 23:19 CVSS 5.9

RemediationAI

Monitor vendor advisories for patches. Apply mitigations such as network segmentation, access restrictions, and monitoring.

Affected VersionsENISA

ServiceStack 8.4.0

Affected Packages

euvd servicestack no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Improper Input Validation (CWE-20).

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.9 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Executive ViewAI

Why It Matters

CVE-2025-6444 presents moderate security risk, a input validation vulnerability rated CVSS 5.9. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: deploy WAF rules, restrict network access, enable logging.

Threat Intelligence Overview

EPSS Score
0.1%
Top 80% exploitable
Data Quality
4 sources
Confidence: Medium

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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Low

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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