Reference page — cumulative record through Wednesday, October 7, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-30666

CVE-2021-30666HIGH

Apple iOS

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   R  U  H  H  H    8.8   .0300   86.9   YES

AFFECTED
  Product  Versions       Fixed
  iOS      unspecified –  —

TIMELINE
  Apr 13  Reserved by apple
  Sep 8   Published (CNA: apple)
  Nov 3   Added to CISA KEV, remediation due 2021-11-17

CWE-119 · CNA: apple · CVSS v3.1 · 2 references · KEV due November 17, 2021

Description

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..

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
April 13, 2021	Reserved	Reserved by apple
September 8, 2021	Published	Published (CNA: apple)
November 3, 2021	KEV ADDED	Added to CISA KEV, remediation due 2021-11-17

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Apple	iOS	—	unspecified	—

Weaknesses

CWE-119

References (2)

https://support.apple.com/en-us/HT212341 [x_refsource_MISC]
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30666 [government-resource]

Authoritative record: CVE-2021-30666 at cve.org

Vendors: apple

Weaknesses: CWE-119

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-30666 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, October 7, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.