{"schemaVersion":3,"id":"CVE-2021-30666","aliases":["UBUNTU-CVE-2021-30666","DEBIAN-CVE-2021-30666"],"status":"published","duplicateOf":null,"title":"Apple iOS WebKit Buffer Overflow Vulnerability","description":"A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..","dates":{"published":"2021-09-08T14:25:25.000Z","modified":"2025-10-21T23:25:34.810Z","reserved":null,"kevAdded":["2021-11-03T00:00:00.000Z"],"kevDue":["2021-11-17T00:00:00.000Z"]},"cvss":{"headline":{"score":8.8,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":7.2,"impact":9.8,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":7.2,"impact":9.8,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":6.8,"severity":"medium","vector":"AV:N/AC:M/Au:N/C:P/I:P/A:P","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.02998,"percentile":0.87164,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.02998},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.02998,"percentile":0.87164}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.02998,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.02998,"percentile":0.87164}]},"kev":{"state":"listed","entries":[{"source":"cisa","sourceLabel":"CISA","dateAdded":"2021-11-03T00:00:00.000Z","dueDate":"2021-11-17T00:00:00.000Z","requiredAction":"Apply updates per vendor instructions.","name":"Apple iOS WebKit Buffer Overflow Vulnerability","description":"Apple iOS WebKit contains a buffer-overflow vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.","notes":[{"type":"url","href":"https://nvd.nist.gov/vuln/detail/CVE-2021-30666","label":"nvd.nist.gov/vuln/detail/CVE-2021-30666"}],"vendor":"Apple","product":"iOS","ransomware":false,"ransomwareUse":"Unknown","exploitationType":null}],"listedCount":1,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":true,"entry":{"source":"cisa","sourceLabel":"CISA","dateAdded":"2021-11-03T00:00:00.000Z","dueDate":"2021-11-17T00:00:00.000Z","requiredAction":"Apply updates per vendor instructions.","name":"Apple iOS WebKit Buffer Overflow Vulnerability","description":"Apple iOS WebKit contains a buffer-overflow vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.","notes":[{"type":"url","href":"https://nvd.nist.gov/vuln/detail/CVE-2021-30666","label":"nvd.nist.gov/vuln/detail/CVE-2021-30666"}],"vendor":"Apple","product":"iOS","ransomware":false,"ransomwareUse":"Unknown","exploitationType":null}},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-119","name":"Improper Restriction of Operations within the Bounds of a Memory Buffer","description":"The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.","type":"weakness","status":"Stable","abstraction":"Class","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/119.html"}],"affected":[{"vendor":"apple","product":"ios","name":"iOS","label":"ios","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ unspecified, < 12.5","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ unspecified, < 12.5","eol":null,"hubHref":"/vendor/apple/ios"},{"vendor":"apple","product":"iphone_os","name":"iphone os","label":"iphone_os","ecosystem":null,"cpePart":"o","purl":null,"purlType":null,"versions":[{"text":"< 12.5.3","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 12.5.3","eol":{"isEol":null,"eolDate":null,"matchMethod":"cpe","cycle":null,"product":{"name":"ios","label":"Apple iOS","category":"os"}},"hubHref":"/vendor/apple/iphone_os"},{"vendor":"debian","product":"webkit2gtk","name":"webkit2gtk","label":"webkit2gtk","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/webkit2gtk","purlType":"deb","versions":[{"text":"< 2.26.1-2","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 2.26.1-2","eol":null,"hubHref":null},{"vendor":"debian","product":"wpewebkit","name":"wpewebkit","label":"wpewebkit","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/wpewebkit","purlType":"deb","versions":[{"text":"< 2.26.3-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 2.26.3-1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"qtwebkit-opensource-src","name":"qtwebkit-opensource-src","label":"qtwebkit-opensource-src","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/qtwebkit-opensource-src","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"qtwebkit-source","name":"qtwebkit-source","label":"qtwebkit-source","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/qtwebkit-source","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"webkit2gtk","name":"webkit2gtk","label":"webkit2gtk","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/webkit2gtk","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null},{"text":"< 2.26.1-0ubuntu0.18.04.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"All versions (No fix recorded) | < 2.26.1-0ubuntu0.18.04.1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"webkitgtk","name":"webkitgtk","label":"webkitgtk","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/webkitgtk","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"wpewebkit","name":"wpewebkit","label":"wpewebkit","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/wpewebkit","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null}],"affectedCount":9,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://support.apple.com/en-us/HT212341","label":"support.apple.com/en-us/HT212341","hostname":"support.apple.com","tags":["X Refsource MISC","Release Notes","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30666","label":"www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30666","hostname":"www.cisa.gov","tags":["Government Resource","Third Party Advisory","US Government Resource"]},{"url":"https://ubuntu.com/security/CVE-2021-30666","label":"ubuntu.com/security/CVE-2021-30666","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-30666","label":"www.cve.org/CVERecord?id=CVE-2021-30666","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","label":"www.cisa.gov/known-exploited-vulnerabilities-catalog","hostname":"www.cisa.gov","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-30666","label":"security-tracker.debian.org/tracker/CVE-2021-30666","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["DSA-4558-1","OPENSUSE-SU-2022:0182-1","OPENSUSE-SU-2024:11506-1","RHSA-2020:4035","RHSA-2020:4451","RHSA-2025:10364","SUSE-SU-2022:0142-1","SUSE-SU-2022:0182-1","SUSE-SU-2022:0182-2","SUSE-SU-2022:0183-1"],"duplicates":[],"related":["OPENSUSE-SU-2022:0182-1","OPENSUSE-SU-2024:11506-1","SUSE-SU-2022:0142-1","SUSE-SU-2022:0182-1","SUSE-SU-2022:0182-2","SUSE-SU-2022:0183-1"]},"timeline":[{"kind":"published","date":"2021-09-08T14:25:25.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"kev-added","date":"2021-11-03T00:00:00.000Z","label":"Added to CISA KEV","detail":"Apple iOS WebKit Buffer Overflow Vulnerability","source":"cisa"},{"kind":"kev-due","date":"2021-11-17T00:00:00.000Z","label":"CISA remediation due","detail":"Apply updates per vendor instructions.","source":"cisa"},{"kind":"modified","date":"2025-10-21T23:25:34.810Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":85,"level":"critical","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T15:48:09.782Z","stale":false,"partial":false}}