Vulnerability

CVE-2021-30666

High· 8.8KEVCVSS8.8EPSS1%

.rules3/5

Apple iOS WebKit Buffer Overflow Vulnerability

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.

Threat signal

98/100

Severe

Severity

high

CVSS

8.8

EPSS

Active

KEV

CISA KEV — actively exploited

1669d overdue

AffectedApple — iOS

Added to KEV

2021-11-03

Federal patch due (BOD 22-01)

2021-11-17

Required action (CISA verbatim)

Apply updates per vendor instructions.

Vendor advisory + references

https://nvd.nist.gov/vuln/detail/CVE-2021-30666

CISA 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.”

CVSS

v3.1Open in FIRST calculator →

8.8/ 10HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionRequiredRequires user action (click, file open, etc).
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

1.18%

probability of exploitation in next 30 days

p79

higher than 79% of all CVEs

3-day trend↑ 0pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2021-30666. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: yes
impact: total
mission: support

Lifecycle

2021-11-03Added to CISA KEVransomware: Unknown
2021-11-03Published
2021-11-17Federal patch due (BOD 22-01)
2023-06-12Vendor advisory · amazon-linuxALAS2-2023-2088 — ALAS2-2023-2088 (important): webkitgtk4
2026-06-12Last modified1 source

Entity graph

2 nodes · 1 edges · click to pivot

CVEActorVendor advisoryIOCNews

Vendor advisories

amazon-linuxALAS2-2023-2088ALAS2-2023-2088 (important): webkitgtk4

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.