CVE-2021-30666 (GCVE-0-2021-30666)

Vulnerability from cvelistv5 – Published: 2021-09-08 14:25 – Updated: 2025-10-21 23:25
VLAI? CISA KEV
Summary
A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..
Severity ?
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE
  • Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.
Assigner
References
Impacted products
Vendor Product Version
Apple iOS Affected: unspecified , < 12.5 (custom)
Create a notification for this product.
CISA KEV
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 1d19fd10-b20c-4e73-84c4-d3dc8162e70b

Vulnerability ID: CVE-2021-30666

Status: Confirmed

Status Updated: 2021-11-03 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2021-11-03
Asserted: 2021-11-03
Scope
Notes: KEV entry: Apple iOS WebKit Buffer Overflow Vulnerability | Affected: Apple / iOS | Description: Apple iOS WebKit contains a buffer-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. | Due date: 2021-11-17 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): https://nvd.nist.gov/vuln/detail/CVE-2021-30666
Evidence

Type: Vendor Report

Signal: Successful Exploitation

Confidence: 80%

Source: cisa-kev

Details
Cwes CWE-119
Feed CISA Known Exploited Vulnerabilities Catalog
Product iOS
Due Date 2021-11-17
Date Added 2021-11-03
Vendorproject Apple
Vulnerabilityname Apple iOS WebKit Buffer Overflow Vulnerability
Knownransomwarecampaignuse Unknown
References
Created: 2026-02-02 13:26 UTC | Updated: 2026-02-06 07:53 UTC
Show details on NVD website
To clipboard 

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Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.