{"cve":"CVE-1999-1591","nvd":{"published":"1999-12-31T05:00:00.000","modified":"2026-06-16T21:50:47.373","status":"Modified","description":"Microsoft Internet Information Services (IIS) server 4.0 SP4, without certain hotfixes released for SP4, does not require authentication credentials under certain conditions, which allows remote attackers to bypass authentication requirements, as demonstrated by connecting via Microsoft Visual InterDev 6.0.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["http://archives.neohapsis.com/archives/ntbugtraq/1998-1999/msg00276.html","http://archives.neohapsis.com/archives/ntbugtraq/1998-1999/msg00277.html","http://www.securityfocus.com/bid/190","http://archives.neohapsis.com/archives/ntbugtraq/1998-1999/msg00276.html","http://archives.neohapsis.com/archives/ntbugtraq/1998-1999/msg00277.html"],"products":["microsoft:internet_information_server","microsoft:visual_interdev"],"source":"nvd","synced_at":"2026-10-19T19:33:01.030757803+00:00"},"epss":{"cve":"CVE-1999-1591","score":0.1127,"percentile":0.9597,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}