CVE record · CVE-2021-30666

Buffer overflow in Apple iOS

CVSS 8.8 HighCriticalIn CISA KEVEPSS 0.030 · 87th percentile

Critical, because:

In CISA’s KEV catalogue since 3 Nov 2021: it is known to be exploited.

Published by the CVE Program (CNA: apple) at 8 Sept 2021, 14:25 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
Apple	iOS	affected unspecified to before 12.5 custom

Identifiers: CVE-2021-30666
CNA: apple
Weakness (CWE): CWE-119
Tags: Apple iOS
Memory corruption
Published: 8 Sept 2021
Updated: 21 Oct 2025

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.8	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	ADP (CISA-ADP)

CISA KEV Listed since 3 Nov 2021: known to be exploited.
EPSS 0.030, the 87th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 8 Sept 2021. New records show when each source confirmed them.

Sources

References from the CNA

support.apple.com/en-us/HT212341

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.