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

Vulnerability from cvelistv5 – Published: 2021-09-08 14:25 – Updated: 2025-10-21 23:25
VLAI CISA KEVIntel
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
SSVC
Exploitation: active Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-01-29 17:25 UTC
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.
  • CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer
Assigner
References
Impacted products
Vendor Product Version
Apple iOS Affected: unspecified , < 12.5 (custom)
Create a notification for this product.
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 57558a2b-fa3a-4c9d-ac66-1a2232e39a2a

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 12:28 UTC | Updated: 2026-02-06 07:17 UTC
KEVIntel
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 9320e44e-b079-4ff2-bff8-a988d94b5979

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: KEVIntel entry: A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content... | Affected: Apple / iOS | CVSS: 8.8 (HIGH) | Used in malware: unknown | Not yet in CISA KEV: False
Evidence

Type: Public Report

Signal: Successful Exploitation

Confidence: 70%

Source: kevintel

Details
Feed KEVIntel (kevintel.com)
Title A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content...
Vendor Apple
Product iOS
Added Date 2021-11-03T00:00:00.000Z
Cvss Score 8.8
Epss Score None
Cvss Severity HIGH
Epss Percentile None
Used In Malware unknown
Ahead Of Cisa Kev None
Not Yet In Cisa Kev False
References
Created: 2026-06-23 14:04 UTC | Updated: 2026-07-10 06:14 UTC
Show details on NVD website
To clipboard 

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