CVE-2021-30761

KEVApple iOS WebKit Memory Corruption Vulnerability

Description

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.

A memory corruption issue was addressed with improved state management. This issue is fixed in iOS 12.5.4. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

CVSS 3.1 vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

PublishedSep 8, 2021

Last modifiedJun 17, 2026

Added to KEVNov 3, 2021

Remediation dueNov 17, 2021

References

support.apple.com/en-us/HT212548Release NotesVendor Advisory
cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30761Third Party AdvisoryUS Government Resource

0 recent articles mention this CVE

Risk assessment · High

Actively exploited. Patch immediately.

Exploitation: Confirmed in the wild (CISA KEV)
Federal remediation deadline: Overdue by 1805 days
CVSS: 8.8 HIGH
EPSS (30-day exploit probability): 10.5% · top 4% of all CVEs
Weakness: CWE-787
Attack vector: Network, remotely reachable

Recommended actions

1.Apply updates per vendor instructions.
2.Treat as emergency change: patch or isolate internet-facing instances first.
3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

Assessment is derived automatically from the live signals above; verify against your own asset inventory.