CVE-2021-30666
Apple iOS WebKit Buffer Overflow Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. 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
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 3.00% probability · 87th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 3 November 2021 · due 17 November 2021
- Weakness
- CWE-119
- Affected
- apple/iphone os
- Source
- product-security@apple.com
EPSS 3.0% since 30 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-30666
References
- https://support.apple.com/en-us/HT212341Release Notes, Vendor Advisory
- https://support.apple.com/en-us/HT212341Release Notes, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30666Third Party Advisory, US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.