Threats / Apple / CVE-2021-30858
CVE-2021-30858
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Apple iOS, iPadOS, and macOS vulnerability
A use-after-free vulnerability in WebKit affects Apple iOS, iPadOS, and macOS, allowing remote code execution through maliciously crafted web content.
Verdict
Today item — known-exploited.
This vulnerability enables arbitrary code execution on affected Apple devices when users interact with malicious web content. The flaw affects WebKit-based browsers and applications, creating a direct attack surface for remote exploitation without user interaction beyond normal browsing.
CISA KEV Yes · 2021-11-034EPSS 0.13486 (verify live)5Exploit Public PoC6CVSS 8.8 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
7 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 0.13486 — 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, iOS, iPadOS, and macOS. 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 71 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
I craft malicious web content designed to trigger the use-after-free condition in WebKit's HTML parser.
Business
User devices become vulnerable to remote code execution when visiting attacker-controlled or compromised websites.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I host the malicious content on a website or distribute it through compromised legitimate sites to maximize exposure.
Business
Attack surface expands across all users accessing affected web properties through Safari or WebKit-dependent applications.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code on compromised devices to establish persistence, steal data, or pivot to other systems.
Business
Confidentiality, integrity, and availability of affected devices are compromised, with potential for data exfiltration and lateral movement.
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