CVE-2025-6444 json
ServiceStack GetErrorResponse Improper Input Validation NTLM Relay Vulnerability
published 2025-06-25 16 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-19133
- cvss
- 5.9
- version 3.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 42%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- servicestack servicestack 8.6
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 16 mo ago
Exploit prediction
0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.0 | 5.9 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVD | 3.1 | 5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
Affected products
- ServiceStack ServiceStack
Classification
- Weakness
-
- CWE-20 Improper Input Validation
References
-
zerodayinitiative.com
/advisories/ZDI-25-415/
third-party-advisory
Sources
- CVE List CVE-2025-6444
- NVD CVE-2025-6444
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