Threats / Apple / CVE-2021-30661
CVE-2021-30661
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Apple Multiple Products vulnerability
Use-after-free vulnerability in WebKit affecting Apple's iOS, iPadOS, macOS, tvOS, watchOS, and Safari. Processing maliciously crafted web content enables arbitrary code execution.
Verdict
Today item — known-exploited.
A use-after-free flaw in WebKit allows remote code execution through malicious web content. The vulnerability affects multiple Apple platforms and any third-party products relying on WebKit for HTML processing. Active exploitation in the wild has been confirmed.
CISA KEV Yes · 2021-11-034EPSS 0.04528 (verify live)5CVSS 8.8 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
8 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03).
Probability (EPSS)
EPSS 0.04528 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) · Affected: Apple, Multiple Products. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-416 Use After Free — weakness family: Memory safety.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 56 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
Craft malicious web content designed to trigger use-after-free conditions in WebKit's memory management during HTML parsing.
Business
Compromise of user devices across multiple platforms creates exposure to data theft, credential harvesting, and persistent system compromise.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
Host or distribute the malicious content via compromised websites, advertisements, or social engineering to reach target users.
Business
Widespread device infections undermine customer trust and create liability for affected organizations relying on vulnerable platforms.
3
Lateral reach — past segmentation narrative 3
Attacker
Execute arbitrary code with the privileges of the affected application or user session upon successful exploitation.
Business
Attackers gain capability to exfiltrate sensitive data, install malware, or pivot to other systems within enterprise networks.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05