Windows NT Local Security Authority (LSA) allows remote attackers to cause a denial of service via malformed arguments to the LsaLookupSids function which looks up the SID, aka "Malformed Security Identifier Request."
Conclusion & alert: CVE-1999-0995 is rated Moderate Risk (60.3/100): CVSS High severity, with high exploitation likelihood (EPSS 21.82%, 97th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. 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 | 2026-06-15 | 27.90% | 21.82% | -6.08% |
| 2 | 2025-03-30 | 13.52% | 27.90% | +14.39% |
| 3 | 2025-03-29 | — | 13.52% | — |
Full EPSS history (8 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.8 | 2.0 | HIGH |
|
10.0 | 6.9 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| microsoft | windows_nt | 4.0 | cpe:2.3:o:microsoft:windows_nt:4.0:*:*:*:*:*:*:* |
| microsoft | windows_nt | 4.0 | cpe:2.3:o:microsoft:windows_nt:4.0:*:server:*:*:*:*:* |
| microsoft | windows_nt | 4.0 | cpe:2.3:o:microsoft:windows_nt:4.0:*:terminal_server:*:*:*:*:* |
| microsoft | windows_nt | 4.0 | cpe:2.3:o:microsoft:windows_nt:4.0:sp1:enterprise:*:*:*:*:* |