{"id":"CVE-2021-34448","published":"2021-07-16T21:15:09Z","modified":"2026-08-10T19:58:48Z","title":"Microsoft Windows Scripting Engine Memory Corruption Vulnerability","vendor":"Microsoft","product":"Windows","tier":"core","eol":null,"description":{"text":"Scripting Engine Memory Corruption Vulnerability","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is a memory corruption vulnerability in the Scripting Engine component of Microsoft Windows, classified as an out-of-bounds write. An attacker can exploit it remotely over the network without authentication, but it requires a high-complexity attack condition and user interaction, and successful exploitation can lead to high confidentiality and integrity impact.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:13:36Z"},"cvss":{"score":6.8,"severity":"MEDIUM","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","provenance":"source","from":"NVD"},"epss":{"score":0.40062,"percentile":0.98633,"date":"2026-10-31","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-34448","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-07-13","exploitedFirstSeen":"2021-07-13","ransomware":false,"evidence":[{"url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2021-Jul","date":"2021-07-13"},{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2021-07-13"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"}],"evidenceTotal":3,"provenance":"source"},"exploited":true,"otx":null,"cwes":[{"id":"CWE-787","name":"Out-of-bounds Write"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34448","tags":["Patch","Vendor Advisory"]},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34448","tags":["Patch","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34448","tags":["US Government Resource"]}],"techniques":[{"id":"T1189","name":"Drive-by Compromise","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Drive-by via user visiting malicious web content","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"Scripting Engine Memory Corruption Vulnerability","start":0,"end":48}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1203","name":"Exploitation for Client Execution","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Memory corruption yields code execution in scripting engine","mappingType":"primary_impact","evidence":[{"from":"description","quote":"Scripting Engine Memory Corruption Vulnerability","start":0,"end":48}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-21103","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-21103","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1189"],"provenance":"ai"},{"stage":"primary","techniques":["T1203"],"provenance":"ai"}],"timeline":[{"date":"2021-07-13","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2021-Jul","provenance":"source"},{"date":"2021-07-16","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-34448","provenance":"source"},{"date":"2021-11-03","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2021-11-03","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-21103","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":110},"priority":{"score":59.5,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 1937 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":19.73,"detail":"percentile 0.9863"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":0.0,"detail":"0 pulses"},{"name":"CVSS severity","points":4.76,"detail":"base score 6.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]},"lineage":{"familyId":"fam-class-microsoft-windows-cwe-787"}}