Is CVE-2021-30663 in the CISA KEV catalog?

Yes. CVE-2021-30663 is on the CISA Known Exploited Vulnerabilities list, added 2021-11-03.

What is the CVSS severity of CVE-2021-30663?

CVE-2021-30663 has a CVSS v3 base score of 8.8 (HIGH).

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

CVE-2021-30663 has an EPSS score of 3.47% (88th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-30663

HIGHCISA KEVEPSS 88th pctl

8.8

CVSS v3

NVD

Description

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.

CWE-190Integer Overflow

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploit Intelligence

3.47%probability of exploitation in 30 days

88thpercentile

Elevated risk: more likely to be exploited than 88% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Apple Multiple Products WebKit Integer Overflow Vulnerability

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.

Apply updates per vendor instructions.

Remediation due: 2021-11-17

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-23.