{"id":"CVE-2021-1870","published":"2021-04-02T19:15:20Z","modified":"2026-06-17T03:32:41Z","title":"Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability","vendor":"Apple","product":"iOS, iPadOS, and macOS","tier":"core","eol":null,"description":{"text":"A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..","provenance":"source","from":"NVD"},"summary":{"text":"A logic flaw in the WebKit browser engine of Apple's iOS, iPadOS, and macOS allows improper validation to be bypassed. A remote attacker can exploit it without authentication, user interaction, or special configuration to execute arbitrary code.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:12:32Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.0771,"percentile":0.94611,"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-2021-1870","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-01-26","exploitedFirstSeen":"2021-01-26","ransomware":false,"evidence":[{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2021-01-26"},{"url":"https://support.apple.com/kb/HT212146","date":"2021-01-26"},{"url":"https://support.apple.com/kb/HT212147","date":"2021-02-01"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"}],"evidenceTotal":4,"provenance":"source"},"exploited":true,"otx":null,"cwes":[{"id":"CWE-1173","name":"Improper Use of Validation Framework"}],"references":[{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JN6ZOD62CTO54CHTMJTHVEF6R2Y532TJ/","tags":["Broken Link","Mailing List"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L3L6ZZOU5JS7E3RFYGLP7UFLXCG7TNLU/","tags":["Broken Link","Mailing List"]},{"url":"https://security.gentoo.org/glsa/202104-03","tags":["Third Party Advisory"]},{"url":"https://support.apple.com/en-us/HT212146","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212147","tags":["Release Notes","Vendor Advisory"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JN6ZOD62CTO54CHTMJTHVEF6R2Y532TJ/","tags":["Broken Link","Mailing List"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L3L6ZZOU5JS7E3RFYGLP7UFLXCG7TNLU/","tags":["Broken Link","Mailing List"]},{"url":"https://security.gentoo.org/glsa/202104-03","tags":["Third Party Advisory"]},{"url":"https://support.apple.com/en-us/HT212146","tags":["Release Notes","Vendor Advisory"]},{"url":"https://support.apple.com/en-us/HT212147","tags":["Release Notes","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1870","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Remote unauthenticated attacker exploits the logic flaw.","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"A remote attacker may be able to cause arbitrary code execution","start":193,"end":256}],"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: Successful exploitation yields arbitrary code execution.","mappingType":"primary_impact","evidence":[{"from":"description","quote":"A remote attacker may be able to cause arbitrary code execution","start":193,"end":256}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-7334","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-7334","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2021-01-26","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","provenance":"source"},{"date":"2021-04-02","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-1870","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-2021-7334","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":215},"priority":{"score":60.8,"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 2105 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":18.92,"detail":"percentile 0.9461"},{"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":6.86,"detail":"base score 9.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}