Threats / Apple / CVE-2023-42917
CVE-2023-42917
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Apple Multiple Products vulnerability
Apple WebKit memory corruption vulnerability in iOS, iPadOS, macOS, and Safari enables remote code execution through maliciously crafted web content. Affects multiple Apple products and third-party applications using WebKit.
Verdict
Today item — known-exploited.
Out-of-bounds write vulnerability in WebKit HTML processing allows unauthenticated remote attackers to execute arbitrary code by delivering malicious web content to vulnerable browsers and applications. Active exploitation observed in the wild.
CISA KEV Yes · 2023-12-044EPSS 0.09295 (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
6 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 2023-12-04).
Probability (EPSS)
EPSS 0.09295 — 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-787 Out-of-bounds Write — 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 4 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 HTML or web content designed to trigger out-of-bounds memory write in WebKit parser
Business
User device compromised through routine web browsing without additional user interaction required
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
Deliver payload via compromised website, ad network, or direct link to target victim's browser or WebKit-dependent application
Business
Attack scales across Safari users and any third-party applications relying on WebKit for content rendering
3
Lateral reach — past segmentation narrative 3
Attacker
Exploit memory corruption to achieve arbitrary code execution with browser or application privileges
Business
Attacker gains ability to steal credentials, install malware, exfiltrate data, or establish persistent access
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
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by appleCNA
Credited with finding itNo finder is named in the public CVE record or the scanned vendor advisory — attribution scoped to the sources checked.
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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