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Known Exploited Vulnerability
8.8
HIGH CVSS 3.1
CVE-2021-30663
Apple Multiple Products WebKit Integer Overflow Vulnerability - [Actively Exploited]
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.

INFO

Published Date :

Sept. 8, 2021, 3:15 p.m.

Last Modified :

Oct. 23, 2025, 2:55 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

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.

Notes :

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

Affected Products

The following products are affected by CVE-2021-30663 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Apple macos
2 Apple iphone_os
3 Apple tvos
4 Apple safari
5 Apple ipados
6 Apple macos
: Total Affected Vendor : 1 | Products : 6
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 2.0 MEDIUM [email protected]
CVSS 3.1 HIGH [email protected]
CVSS 3.1 HIGH 134c704f-9b21-4f2e-91b3-4a467353bcc0
Solution
This addresses a WebKit integer overflow vulnerability that could lead to arbitrary code execution.
  • Update affected packages for your operating system.
  • Upgrade to the latest version of Safari.
  • Upgrade to the latest version of iOS.
  • Upgrade to the latest version of iPadOS.
Public PoC/Exploit Available at Github

CVE-2021-30663 has a 2 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-30663.

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

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-30663 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-30663 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

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awslabs/Chatbot-to-help-security-teams-perform-vulnerability-assessments

None

Python Dockerfile

Updated: 1 month ago
28 stars 2 fork 2 watcher
Born at : Jan. 3, 2025, 9:23 p.m. This repo has been linked 9 different CVEs too.
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Ostorlab/KEV

Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.

cisa-kev vulnerability 0day cisa exploits

Updated: 2 weeks, 6 days ago
588 stars 42 fork 42 watcher
Born at : April 19, 2022, 8:58 a.m. This repo has been linked 1290 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-30663 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2021-30663 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Modified Analysis by [email protected]

    Oct. 23, 2025

    Action Type Old Value New Value
    Changed Reference Type Apple Inc.: https://support.apple.com/en-us/HT212335 Types: Vendor Advisory Apple Inc.: https://support.apple.com/en-us/HT212335 Types: Release Notes, Vendor Advisory
    Changed Reference Type Apple Inc.: https://support.apple.com/en-us/HT212336 Types: Vendor Advisory Apple Inc.: https://support.apple.com/en-us/HT212336 Types: Release Notes, Vendor Advisory
    Changed Reference Type Apple Inc.: https://support.apple.com/en-us/HT212341 Types: Vendor Advisory Apple Inc.: https://support.apple.com/en-us/HT212341 Types: Release Notes, Vendor Advisory
    Changed Reference Type Apple Inc.: https://support.apple.com/en-us/HT212532 Types: Vendor Advisory Apple Inc.: https://support.apple.com/en-us/HT212532 Types: Release Notes, Vendor Advisory
    Changed Reference Type Apple Inc.: https://support.apple.com/en-us/HT212534 Types: Vendor Advisory Apple Inc.: https://support.apple.com/en-us/HT212534 Types: Release Notes, Vendor Advisory
    Added Reference Type CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663 Types: Third Party Advisory, US Government Resource
    Changed Reference Type CVE: https://support.apple.com/en-us/HT212534 Types: Vendor Advisory CVE: https://support.apple.com/en-us/HT212534 Types: Release Notes, Vendor Advisory
    Changed Reference Type CVE: https://support.apple.com/en-us/HT212532 Types: Vendor Advisory CVE: https://support.apple.com/en-us/HT212532 Types: Release Notes, Vendor Advisory
    Changed Reference Type CVE: https://support.apple.com/en-us/HT212341 Types: Vendor Advisory CVE: https://support.apple.com/en-us/HT212341 Types: Release Notes, Vendor Advisory
    Changed Reference Type CVE: https://support.apple.com/en-us/HT212336 Types: Vendor Advisory CVE: https://support.apple.com/en-us/HT212336 Types: Release Notes, Vendor Advisory
    Changed Reference Type CVE: https://support.apple.com/en-us/HT212335 Types: Vendor Advisory CVE: https://support.apple.com/en-us/HT212335 Types: Release Notes, Vendor Advisory
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 22, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 21, 2025

    Action Type Old Value New Value
    Removed Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 21, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663
  • Modified Analysis by [email protected]

    Jul. 30, 2025

    Action Type Old Value New Value
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jul. 30, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Removed CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
  • Modified Analysis by [email protected]

    Feb. 14, 2025

    Action Type Old Value New Value
    Changed CPE Configuration OR *cpe:2.3:a:apple:macos:*:*:*:*:*:*:*:* versions from (including) 11.0 up to (excluding) 11.3.1 *cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:* versions up to (excluding) 14.1.1 *cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5.1 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions up to (excluding) 12.5.3 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5.1 *cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:* versions up to (excluding) 14.6 OR *cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:* versions up to (excluding) 14.1.1 *cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5.1 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions up to (excluding) 12.5.3 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5.1 *cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:* versions from (including) 11.0 up to (excluding) 11.3.1 *cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:* versions up to (excluding) 14.6
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Feb. 03, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Added CWE CWE-190
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://support.apple.com/en-us/HT212335
    Added Reference https://support.apple.com/en-us/HT212336
    Added Reference https://support.apple.com/en-us/HT212341
    Added Reference https://support.apple.com/en-us/HT212532
    Added Reference https://support.apple.com/en-us/HT212534
  • CVE CISA KEV Update by 9119a7d8-5eab-497f-8521-727c672e3725

    May. 16, 2024

    Action Type Old Value New Value
    Changed Vulnerability Name Apple Multiple Products Integer Overflow Vulnerability Apple Multiple Products WebKit Integer Overflow Vulnerability
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • Reanalysis by [email protected]

    Feb. 02, 2024

    Action Type Old Value New Value
  • Initial Analysis by [email protected]

    Sep. 16, 2021

    Action Type Old Value New Value
    Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism
    Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Changed Reference Type https://support.apple.com/en-us/HT212335 No Types Assigned https://support.apple.com/en-us/HT212335 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212336 No Types Assigned https://support.apple.com/en-us/HT212336 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212341 No Types Assigned https://support.apple.com/en-us/HT212341 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212532 No Types Assigned https://support.apple.com/en-us/HT212532 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212534 No Types Assigned https://support.apple.com/en-us/HT212534 Vendor Advisory
    Added CWE NIST CWE-190
    Added CPE Configuration OR *cpe:2.3:a:apple:macos:*:*:*:*:*:*:*:* versions from (including) 11.0 up to (excluding) 11.3.1 *cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:* versions up to (excluding) 14.1.1 *cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5.1 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions up to (excluding) 12.5.3 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5.1 *cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:* versions up to (excluding) 14.6
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 8.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact
Base CVSS Score: 6.8
Access Vector
Access Complexity
Authentication
Confidentiality Impact
Integrity Impact
Availability Impact
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

0.42 }} -0.19%

score

0.61473

percentile