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CVE-2021-30663

Apple Multiple Products WebKit Integer Overflow

8.8 HIGHActively exploited (CISA KEV)EPSS 3.52%
  1. Published8 Sept 2021
  2. Added to CISA KEV3 Nov 2021
  3. Remediation due17 Nov 2021
Actively exploited (CISA KEV)

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.

Added to KEV: 3 Nov 2021Federal remediation due: 17 Nov 2021

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

Apple Safari< 14.1.1
Apple iPadOS≥ 14.0 < 14.5.1
Apple iPhone OS≥ 14.0 < 14.5.1 · < 12.5.3
Apple macOS≥ 11.0 < 11.3.1
Apple Tvos< 14.6

Remediation

Fixed in
Apple Safari≥ 14.1.1
Apple iPadOS≥ 14.5.1
Apple iPhone OS≥ 14.5.1
Apple macOS≥ 11.3.1
Apple Tvos≥ 14.6

References

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Frequently asked

Is CVE-2021-30663 being actively exploited?

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

How severe is CVE-2021-30663?

CVE-2021-30663 has a CVSS 3.1 base score of 8.8, rated high. EPSS estimates a 3.52% probability of exploitation.

Which products are affected by CVE-2021-30663?

Affected products include Apple Safari, Apple iPadOS, Apple iPhone OS, Apple macOS, Apple Tvos.

How do I fix CVE-2021-30663?

Upgrade affected software to a fixed version, for example Apple Safari 14.1.1, Apple iPadOS 14.5.1, Apple iPhone OS 14.5.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-30663 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.