CVE-1999-0391
CVE-1999-0391 is a high-severity vulnerability in Microsoft Terminal Server with a CVSS 2.0 base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: High (CVSS 2.0 base score 7.5)
- EPSS exploit prediction: 5% (91st percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Microsoft Terminal Server
- Published:
- Last modified:
Description
The cryptographic challenge of SMB authentication in Windows 95 and Windows 98 can be reused, allowing an attacker to replay the response and impersonate a user.
Frequently asked questions
- What is CVE-1999-0391?
- The cryptographic challenge of SMB authentication in Windows 95 and Windows 98 can be reused, allowing an attacker to replay the response and impersonate a user.
- How severe is CVE-1999-0391?
- CVE-1999-0391 has a CVSS 2.0 base score of 7.5, rated high severity.
- Is CVE-1999-0391 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-1999-0391?
- CVE-1999-0391 primarily affects Microsoft Terminal Server. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-1999-0391?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-1999-0391 published?
- CVE-1999-0391 was published on 1999-01-05 and last updated on 2026-06-16.
References
Affected products (13)
- cpe:2.3:a:microsoft:terminal_server:*:*:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_2000:*:*:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:3.5.1:sp1:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:3.5.1:sp2:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:3.5.1:sp3:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:3.5.1:sp4:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:3.5.1:sp5:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:4.0:*:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:4.0:sp1:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:4.0:sp2:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:4.0:sp3:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:4.0:sp4:*:*:*:*:*:*
- cpe:2.3:o:microsoft:windows_nt:4.0:sp5:*:*:*:*:*:*
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