CVE-1999-1476

A bug in Intel Pentium processor (MMX and Overdrive) allows local users to cause a denial of service (hang) in Intel-based operating systems such as Windows NT and Windows 95, via an invalid instruction, aka the "Invalid Operand with Locked CMPXCHG8B Instruction" problem.

Published: 1999-12-31 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-1999-1476 is rated Low Risk (15.7/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.29%). Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-1999-1476

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 0.06% 0.29% +0.23%
2 2025-03-17 0.04% 0.06% +0.02%
3 2023-03-07 — 0.04% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-1999-1476

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
2.1 2.0 LOW
AV:L/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-1999-1476

Affected software / configurations for CVE-1999-1476

Vendor Product Version Raw CPE
intel pentium — cpe:2.3:h:intel:pentium:*:*:mmx:*:*:*:*:*
intel pentuim — cpe:2.3:h:intel:pentuim:*:*:overdrive:*:*:*:*:*

References for CVE-1999-1476

cvelogic Threat Intelligence