What is CVE-2021-30661?

CVE-2021-30661 is a high-severity vulnerability in Apple iOS And Ipados, classified under Use After Free. CVSS score: 8.8/10. Published 2021-09-08.

How severe is CVE-2021-30661?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2021-30661 known to be exploited?

Yes. CVE-2021-30661 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.

Use After Free in Apple iOS And Ipados

CVE-2021-30661

A use after free issue was addressed with improved memory management. This issue is fixed in Safari 14.1, iOS 12.5.3, iOS 14.5 and iPadOS 14.5, watchOS 7.4, tvOS 14.5, macOS Big Sur 11.3. 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..

Vulnerability class: Use-After-Free

Published 2021-09-08 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.045 (91.4th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 91.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.045 · newest: 0.045 · change: 0.000

Affected products

Apple iOS And Ipados — versions unspecified
Apple Ipados
Apple Iphone OS
Apple macOS — versions unspecified
Apple Safari — versions unspecified
Apple tvOS — versions unspecified
Apple watchOS — versions unspecified

Weakness classification (CWE)

CWE-416 — Use After Free

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2021-11-03. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2021-11-17.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

support.apple.com/en-us/HT212317 (Vendor Advisory)
support.apple.com/en-us/HT212323 (Vendor Advisory)
support.apple.com/en-us/HT212324 (Vendor Advisory)
support.apple.com/en-us/HT212325 (Vendor Advisory)
support.apple.com/en-us/HT212341 (Vendor Advisory)
support.apple.com/en-us/HT212318 (Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (Third Party Advisory, US Government Resource)

Frequently asked questions

What is CVE-2021-30661?: CVE-2021-30661 is a high-severity vulnerability in Apple iOS And Ipados, classified under Use After Free. CVSS score: 8.8/10. Published 2021-09-08.
How severe is CVE-2021-30661?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2021-30661 known to be exploited?: Yes. CVE-2021-30661 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.