CVE-2016-4657: in the CISA KEV catalogue
Apple iOS Webkit Memory Corruption Vulnerability. CISA added CVE-2016-4657 to the Known Exploited Vulnerabilities catalogue on 2022-05-24 with a default due date of 2022-06-14. Known ransomware campaign use: Unknown. Forensic triage flag: No.
Apple iOS WebKit contains a memory corruption vulnerability that allows attackers to execute remote code or cause a denial-of-service (DoS) via a crafted web site. 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. (CISA description)
- Vendor / product
- Apple iOS
- CWE
- CWE-119
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 67%, percentile 99 (scored 2026-11-03)
EPSS puts about 67 in 100 odds (67%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2016-4657 in the CISA KEV catalogue?
Yes. CISA added CVE-2016-4657 (Apple iOS Webkit Memory Corruption Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2022-05-24. CISA's default due date for it is 2022-06-14.
Is CVE-2016-4657 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2016-4657. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2016-4657?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2016-4657