{"cve":"CVE-2009-4445","nvd":{"published":"2009-12-29T21:00:24.453","modified":"2026-06-16T23:13:40.907","status":"Modified","description":"Microsoft Internet Information Services (IIS), when used in conjunction with unspecified third-party upload applications, allows remote attackers to create empty files with arbitrary extensions via a filename containing an initial extension followed by a : (colon) and a safe extension, as demonstrated by an upload of a .asp:.jpg file that results in creation of an empty .asp file, related to support for the NTFS Alternate Data Streams (ADS) filename syntax.  NOTE: it could be argued that this is a vulnerability in the third-party product, not IIS, because the third-party product should be applying its extension restrictions to the portion of the filename before the colon.","cvss_v4":null,"cvss_v3":null,"cwes":["CWE-20"],"references":["http://securitytracker.com/id?1023387","http://soroush.secproject.com/downloadable/iis-semicolon-report.pdf","https://exchange.xforce.ibmcloud.com/vulnerabilities/55308","http://securitytracker.com/id?1023387","http://soroush.secproject.com/downloadable/iis-semicolon-report.pdf"],"products":["microsoft:internet_information_services"],"source":"nvd","synced_at":"2026-10-19T19:55:32.599380760+00:00"},"epss":{"cve":"CVE-2009-4445","score":0.12757,"percentile":0.96275,"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."]}