Windows HTTP Services (aka WinHTTP) in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP1 and SP2, Vista Gold and SP1, and Server 2008; and WinINet in Microsoft Internet Explorer 5.01 SP4, 6 SP1, 6 and 7 on Windows XP SP2 and SP3, 6 and 7 on Windows Server 2003 SP1 and SP2, 7 on Windows Vista Gold and SP1, and 7 on Windows Server 2008; allows remote web servers to capture and replay NTLM credentials, and execute arbitrary code, via vectors related to absence of a "credential-reflection protections" opt-in step, aka "Windows HTTP Services Credential Reflection Vulnerability" and "WinINet Credential Reflection Vulnerability."
Conclusion & alert: CVE-2009-0550 is rated High Risk (75/100): CVSS Critical severity, with high exploitation likelihood (EPSS 38.59%, 97th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +3.77% over the last day, indicating growing attacker interest. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2025-12-28 | 34.82% | 38.59% | +3.77% |
| 2 | 2025-12-27 | 38.59% | 34.82% | -3.77% |
| 3 | 2025-10-28 | — | 38.59% | — |
Full EPSS history (29 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 9.3 | 2.0 | HIGH |
|
8.6 | 10.0 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| microsoft | windows_2000 | — | cpe:2.3:o:microsoft:windows_2000:*:sp4:*:*:*:*:*:* |
| microsoft | windows_server_2003 | — | cpe:2.3:o:microsoft:windows_server_2003:*:*:*:*:*:*:*:* |
| microsoft | windows_server_2003 | — | cpe:2.3:o:microsoft:windows_server_2003:*:sp1:*:*:*:*:*:* |
| microsoft | windows_server_2003 | — | cpe:2.3:o:microsoft:windows_server_2003:*:sp1:itanium:*:*:*:*:* |
| microsoft | windows_server_2003 | — | cpe:2.3:o:microsoft:windows_server_2003:*:sp2:*:*:*:*:*:* |
| microsoft | windows_server_2008 | — | cpe:2.3:o:microsoft:windows_server_2008:*:*:itanium:*:*:*:*:* |
| microsoft | windows_server_2008 | — | cpe:2.3:o:microsoft:windows_server_2008:*:*:x32:*:*:*:*:* |
| microsoft | windows_server_2008 | — | cpe:2.3:o:microsoft:windows_server_2008:*:*:x64:*:*:*:*:* |
| microsoft | windows_vista | — | cpe:2.3:o:microsoft:windows_vista:*:*:x64:*:*:*:*:* |
| microsoft | windows_vista | — | cpe:2.3:o:microsoft:windows_vista:*:sp1:*:*:*:*:*:* |
| microsoft | windows_vista | gold | cpe:2.3:o:microsoft:windows_vista:gold:*:*:*:*:*:*:* |
| microsoft | windows_xp | — | cpe:2.3:o:microsoft:windows_xp:*:*:pro_x64:*:*:*:*:* |
| microsoft | windows_xp | — | cpe:2.3:o:microsoft:windows_xp:*:sp2:*:*:*:*:*:* |
| microsoft | windows_xp | — | cpe:2.3:o:microsoft:windows_xp:*:sp2:pro_x64:*:*:*:*:* |
| microsoft | windows_xp | — | cpe:2.3:o:microsoft:windows_xp:*:sp3:*:*:*:*:*:* |
| microsoft | ie | 6.0 | cpe:2.3:a:microsoft:ie:6.0:sp1:*:*:*:*:*:* |
| microsoft | internet_explorer | 5.01 | cpe:2.3:a:microsoft:internet_explorer:5.01:sp4:*:*:*:*:*:* |
| microsoft | internet_explorer | 6 | cpe:2.3:a:microsoft:internet_explorer:6:*:*:*:*:*:*:* |
| microsoft | internet_explorer | 7 | cpe:2.3:a:microsoft:internet_explorer:7:*:*:*:*:*:*:* |
| microsoft | windows_server_2008 | — | cpe:2.3:o:microsoft:windows_server_2008:*:*:*:*:*:*:*:* |
| microsoft | windows_server_2008 | — | cpe:2.3:o:microsoft:windows_server_2008:*:*:32_bit:*:*:*:*:* |
| microsoft | windows_vista | — | cpe:2.3:o:microsoft:windows_vista:*:*:*:*:*:*:*:* |
| microsoft | windows_xp | — | cpe:2.3:o:microsoft:windows_xp:*:*:x64:*:*:*:*:* |
| microsoft | windows_xp | — | cpe:2.3:o:microsoft:windows_xp:*:sp2:x64:*:*:*:*:* |