CVE-2021-30761: in the CISA KEV catalogue
Apple iOS WebKit Memory Corruption Vulnerability. CISA added CVE-2021-30761 to the Known Exploited Vulnerabilities catalogue on 2021-11-03 with a default due date of 2021-11-17. Known ransomware campaign use: Unknown. Forensic triage flag: No.
Apple iOS WebKit contains a memory corruption 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. (CISA description)
- Vendor / product
- Apple iOS
- CWE
- CWE-787
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 11%, percentile 95 (scored 2026-11-03)
EPSS puts about 11 in 100 odds (11%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 95% 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-2021-30761 in the CISA KEV catalogue?
Yes. CISA added CVE-2021-30761 (Apple iOS WebKit Memory Corruption Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2021-11-03. CISA's default due date for it is 2021-11-17.
Is CVE-2021-30761 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2021-30761. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2021-30761?
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-2021-30761