KEV Monitor
← Back to catalog

Apple · Multiple Products

CVE-2021-30663

Apple Multiple Products WebKit Integer Overflow Vulnerability

CISA KEV record

CISA date added
2021-11-03
CISA due date
2021-11-17
Known ransomware use
Unknown

NVD risk context

8.8 HIGH

CVSS is a technical severity score. CISA’s KEV status remains the evidence that this vulnerability is known to be exploited.

View NVD record ↗
Attack vector
Network
The vulnerable service can be reached remotely over a network.
Attack complexity
Low
Exploitation does not require unusual conditions beyond normal attacker control.
Privileges required
None
The attacker does not need an existing account or privileges.
User interaction
Required
A user must take an action, such as opening a file or link.

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.

Required action

Apply updates per vendor instructions.

NVD reference index

Vendor and remediation references

NVD has tagged these sources as vendor advisories, patches, mitigations, or release notes.

Other NVD references (1)

MITRE CWE context

CWE classification

CWE-20 Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

View official MITRE CWE details ↗
CWE-190 Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

View official MITRE CWE details ↗

NVD record timing

NVD record timeline

These dates describe NVD’s record, not CISA’s KEV addition or remediation due date.

NVD published
Sep 08, 2021, 03:15 PM UTC
When NVD first published this CVE record.
NVD last updated
Jun 17, 2026, 03:50 AM UTC
When NVD last changed its analysis or record data.
Advanced: view the technical CVSS vector

This standardized code is intended for security tools and technical analysts. The plain-language risk summary above explains its main points.

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

View NVD record ↗

CISA notes

https://nvd.nist.gov/vuln/detail/CVE-2021-30663