{"id":"CVE-2021-30663","published":"2021-09-08T15:15:13Z","modified":"2026-06-17T03:50:38Z","title":"Apple Multiple Products WebKit Integer Overflow Vulnerability","vendor":"Apple","product":"Multiple Products","tier":"core","eol":null,"description":{"text":"An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is an integer overflow in WebKit, the browser engine used across Apple's products, including iOS, iPadOS, tvOS, Safari, and macOS Big Sur. An attacker can achieve arbitrary code execution by getting a user to process maliciously crafted web content, which requires that the user interact with that content (for example, by visiting a page) and no prior authentication.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:13:41Z"},"cvss":{"score":8.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.03521,"percentile":0.89199,"date":"2026-10-29","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-2021-30663","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-05-03","exploitedFirstSeen":"2021-05-03","ransomware":false,"evidence":[{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2021-05-03"},{"url":"https://support.apple.com/kb/HT212335","date":"2021-05-03"},{"url":"https://support.apple.com/kb/HT212336","date":"2021-05-03"},{"url":"https://support.apple.com/kb/HT212341","date":"2021-05-03"},{"url":"https://support.apple.com/kb/HT212340","date":"2021-05-04"},{"url":"https://support.apple.com/kb/HT212532","date":"2021-05-24"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"}],"evidenceTotal":7,"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-190","name":"Integer Overflow or Wraparound"},{"id":"CWE-20","name":"Improper Input Validation"}],"references":[{"url":"https://support.apple.com/en-us/HT212335","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212336","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212341","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212532","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212534","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212335","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212336","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212341","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212532","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212534","tags":["Release Notes","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663","tags":["Third Party Advisory","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: Malicious web content delivered to victims drives exploitation","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"Processing maliciously crafted web content may lead to arbitrary code execution","start":179,"end":258}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Arbitrary code execution is the direct impact","mappingType":"primary_impact","evidence":[{"from":"description","quote":"Processing maliciously crafted web content may lead to arbitrary code execution","start":179,"end":258}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-17580","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-17580","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1189"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2021-05-03","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","provenance":"source"},{"date":"2021-09-08","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-30663","provenance":"source"},{"date":"2021-11-03","kind":"kev","label":"Added to CISA 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product","points":0.0,"detail":"supported or unknown"}]},"lineage":{"familyId":"fam-class-apple-ios-macos-cwe-20"}}