NTLM credential relay via unrestricted WebRequest creation
Published Jun 25, 2025 · Updated Jun 25, 2025
Improper input validation in ServiceStack 8.4.0 allows remote attackers to relay the current user's NTLM credentials via a crafted URL. HttpUtils.GetErrorResponse passes an untrusted URL to WebRequest.Create, allowing a file:// value to create a FileWebRequest instead of limiting requests to HTTP. Exploitation requires an application to pass attacker-controlled input to this convenience wrapper; the vendor disputes that the wrapper adds risk beyond .NET.
Summary
What happened
Improper input validation in ServiceStack 8.4.0 allows remote attackers to relay the current user's NTLM credentials via a crafted URL. HttpUtils.GetErrorResponse passes an untrusted URL to WebRequest.Create, allowing a file:// value to create a FileWebRequest instead of limiting requests to HTTP. Exploitation requires an application to pass attacker-controlled input to this convenience wrapper; the vendor disputes that the wrapper adds risk beyond .NET.
The record
- CVE
- CVE-2025-6444
- Published
- Jun 25, 2025
- Updated
- Jun 25, 2025
- Vendor
- ServiceStack
- Product
- ServiceStack
- Classifications
- CWE-20, T1187
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 25, 2025CVE publishedPublication date reported by the CVE source.
- Jun 25, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=8.4.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- GetErrorResponse file URL proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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