What is CVE-2021-30900?

CVE-2021-30900 is a high-severity vulnerability in Apple iOS And Ipados, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2021-08-24.

How severe is CVE-2021-30900?

High severity. CVSS v3 base score is 7.8 out of 10.

Is CVE-2021-30900 known to be exploited?

Yes. CVE-2021-30900 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-03-30), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.

Buffer overflow in Apple iOS And Ipados

CVE-2021-30900

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 14.8.1 and iPadOS 14.8.1, iOS 15.1 and iPadOS 15.1. A malicious application may be able to execute arbitrary code with kernel privileges.

Vulnerability class: Buffer Overflow

Published 2021-08-24 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.052 (92.4th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 92nd percentile — 92.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.052 · newest: 0.052 · change: 0.000

Affected products

Apple iOS And Ipados — versions unspecified
Apple Ipados — versions 15.0
Apple Iphone OS — versions 15.0
Apple macOS

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2023-03-30. 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: 2023-04-20.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

support.apple.com/kb/HT212872 (Vendor Advisory)
support.apple.com/en-us/HT212867 (Vendor Advisory)
support.apple.com/en-us/HT212868 (Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2021-30900?: CVE-2021-30900 is a high-severity vulnerability in Apple iOS And Ipados, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2021-08-24.
How severe is CVE-2021-30900?: High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2021-30900 known to be exploited?: Yes. CVE-2021-30900 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-03-30), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.