Is CVE-2021-30663 being actively exploited?

Yes. CVE-2021-30663 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added on November 3, 2021.

What is the CVSS score for CVE-2021-30663?

CVE-2021-30663 has a CVSS 3.1 base score of 8.8 (HIGH).

CVE-2021-30663

HIGH · CVSS 8.8CISA KEV: actively exploitedEPSS 3.5%EU EUVD: exploited

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.

Key facts

CVSS score: 8.8 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-190
EPSS score: 3.5% (89th percentile)
In CISA KEV: Yes, added November 3, 2021
In EU EUVD: Yes (EUVD-2021-17580)
Published: September 8, 2021
NVD last modified: June 17, 2026
Status: Analyzed

CISA Known Exploited Vulnerability

Apple Multiple Products WebKit Integer Overflow Vulnerability

Added to the KEV catalog on November 3, 2021; federal remediation due November 17, 2021.

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-17580 in the EU Vulnerability Database. ENISA flags it as known exploited. Last updated in EUVD on October 21, 2025.

View on the EU Vulnerability Database

Affected products

apple / ipados
apple / iphone os
apple / macos
apple / safari
apple / tvos

Certified products that may be affected

1 FIPS 140 or Common Criteria certified product, from automated matching by sec-certs.org.

Apple macOS 11 Big Sur: Contacts - Apple Inc. - Common Criteria CCEVS-VR-VID-11243-2022 - archived

References

https://support.apple.com/en-us/HT212335(Release Notes, Vendor Advisory)
https://support.apple.com/en-us/HT212336(Release Notes, Vendor Advisory)
https://support.apple.com/en-us/HT212341(Release Notes, Vendor Advisory)
https://support.apple.com/en-us/HT212532(Release Notes, Vendor Advisory)
https://support.apple.com/en-us/HT212534(Release Notes, Vendor Advisory)
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663(Third Party Advisory, US Government Resource)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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