{"id":"CVE-2021-26411","published":"2021-03-11T16:15:13Z","modified":"2026-10-01T21:17:16Z","title":"Microsoft Internet Explorer Memory Corruption Vulnerability","vendor":"Microsoft","product":"Internet Explorer","tier":"core","eol":null,"description":{"text":"Internet Explorer Memory Corruption Vulnerability","provenance":"source","from":"NVD"},"summary":{"text":"A memory corruption flaw in Microsoft Internet Explorer, classified as a use-after-free issue, lives in the browser's rendering and memory-handling code. An attacker who can reach the target over the network can exploit it without authentication or special privileges, but a user must interact with the attacker's content, such as by visiting a malicious page, for the exploit to succeed, and the attack can affect resources beyond the vulnerable component's own security scope.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T06:58:51Z"},"cvss":{"score":8.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L","provenance":"source","from":"NVD"},"epss":{"score":0.81667,"percentile":0.99641,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":true,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-26411","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-03-09","exploitedFirstSeen":"2021-03-09","ransomware":true,"evidence":[{"url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2021-Mar","date":"2021-03-09"},{"url":"https://arstechnica.com/gadgets/2021/03/microsoft-patches-critical-0day-that-north-korea-used-to-target-researchers/","date":"2021-03-09"},{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2021-03-09"},{"url":"https://decoded.avast.io/janvojtesek/magnitude-exploit-kit-still-alive-and-kicking/","date":"2021-07-29"},{"url":"https://www.crowdstrike.com/blog/magniber-ransomware-caught-using-printnightmare-vulnerability/","date":"2021-08-11"},{"url":"https://cybersecurityworks.com/howdymanage/uploads/file/ransomware_index-update-q221-csw.pdf","date":"2021-08-16"},{"url":"https://threatpost.com/inkysquid-exploiting-ie-bugs/168833/","date":"2021-08-29"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"},{"url":"https://cybersecurityworks.com/howdymanage/uploads/file/ransomware-_-2022-spotlight-report_compressed.pdf","date":"2022-01-26"},{"url":"https://cybersecurityworks.com/howdymanage/uploads/file/Spotlight%20Report%20-%20Index%20Update%20Q2%20-%20Q3%20-%20Final%20Version_compressed.pdf","date":"2022-05-18"}],"evidenceTotal":15,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26411","tags":["Patch","Vendor Advisory"]},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26411","tags":["Patch","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26411","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: browser memory corruption via drive-by content","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"Internet Explorer Memory Corruption Vulnerability","start":0,"end":49}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[{"id":"SRC-dd68e1c5c4a187b8f1c3","title":"North Korean APT InkySquid Infects Victims Using Browser Exploits","publisher":"volexity.com","url":"https://www.volexity.com/blog/2021/08/17/north-korean-apt-inkysquid-infects-victims-using-browser-exploits/","date":"2021-08-17","mentions":[{"quote":"CVE-2021-26411","start":5115,"end":5129},{"quote":"On another occasion, CVE-2021-26411 was used, which is another exploit targeting Internet Explorer and legacy versions of Microsoft Edge.","start":5133,"end":5270}]}],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-13217","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-13217","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":0,"earliest":"2021-11-22","earliestUrl":"https://github.com/CrackerCat/CVE-2021-26411","repos":[{"name":"CrackerCat/CVE-2021-26411","url":"https://github.com/CrackerCat/CVE-2021-26411","stars":2,"created":"2021-11-22"}]},"first":{"date":"2021-11-22","source":"PoC-in-GitHub","url":"https://github.com/CrackerCat/CVE-2021-26411"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1189"],"provenance":"ai"}],"timeline":[{"date":"2021-03-09","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV 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