CVE-2021-30663
Apple Multiple Products WebKit Integer Overflow Vulnerability
CVSS
7.8HighExploit odds (EPSS)3.52%Chance of exploitation activity in the next 30 days, higher than 89% of CVEs. Scored 23 Oct 2026FIRST EPSS
CISA required actionApply updates per vendor instructions. CISA KEV
What fixes it
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
Timeline
Description
Apple iOS, iPadOS, macOS, tvOS, and Safari WebKit contain an integer 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.
Text from CVE List
Affected versions 5
- macOSaffected: unspecified before 11.3CVE List
- macOSaffected: unspecified before 14.5CVE List
- macOSaffected: unspecified before 12.5CVE List
- macOSaffected: unspecified before 14.6CVE List
- macOSaffected: unspecified before 14.1CVE List
References 7
- nvd.nist.gov/vuln/detail/CVE-2021-30663Referencevia CISA KEV
- support.apple.com/en-us/HT212532Referencevia CVE List
- support.apple.com/en-us/HT212534Referencevia CVE List
- support.apple.com/en-us/HT212341Referencevia CVE List
- support.apple.com/en-us/HT212335Referencevia CVE List
- support.apple.com/en-us/HT212336Referencevia CVE List
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663Referencevia CVE List