CVE-2021-30900
CVE-2021-30900 is a security flaw in Apple iOS, iPadOS, and macOS, the software on Apple’s iPhones, iPads and Macs. Attackers can run their own code on Apple iOS, iPadOS, and macOS. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 30 Mar 2023.[1]
Apple iOS, iPadOS, and macOS is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Fixed in version 15.1 and 14.8 of iOS and iPadOS.
Description
CISA calls it an out-of-bounds write in Apple iOS, iPadOS, and macOS. In its words: “Apple GPU drivers, included in iOS, iPadOS, and macOS, contain an out-of-bounds write vulnerability that may allow a malicious application to execute code with kernel privileges.”[1]
The CVE record adds: “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.”[2]
The underlying weakness is improper input validation (CWE-20), out-of-bounds write (CWE-787), in MITRE’s list of common software weaknesses.
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| iOS and iPadOS | 15.1 |
| iOS and iPadOS | 14.8 |
Every device with Apple iOS, iPadOS, and macOS needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 30 Mar 2023, 583 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 20 Apr 2023 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 5%. That’s in the top 8% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Apple has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Update Apple iOS, iPadOS, and macOS now.On iPhone and iPad: Settings, General, Software Update. On a Mac: System Settings, General, Software Update. Install it on every Apple device in the house. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 15.1 or later.Fixed in version 15.1 and 14.8 of iOS and iPadOS. Anything older is what attackers are going after.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 5%.[4] |
See also
Other Apple iOS, iPadOS, and macOS flaws
- CVE-2025-43300: out-of-bounds write ·
- CVE-2023-41064: imageIO buffer overflow ·
- CVE-2023-28206: iOSurfaceAccelerator out-of-bounds write ·
- CVE-2022-32917: remote code execution ·
- CVE-2020-9934: input validation ·
- CVE-2022-22620: webkit use-after-free ·
Other Apple flaws
- CVE-2026-86950, Apple devices: out-of-bounds write ·
- CVE-2026-65400, Apple macOS: improper authentication ·
- CVE-2025-43520, Apple devices: classic buffer overflow ·
- CVE-2025-43510, Apple devices: improper locking ·
- CVE-2025-31277, Apple devices: buffer overflow ·
Other improper input validation flaws
- CVE-2026-93952, Arista VeloCloud Orchestrator: improper input validation ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
- CVE-2026-12569, PTC Windchill and FlexPLM: improper input validation ·
- CVE-2026-34910, Ubiquiti UniFi OS: improper input validation ·
- CVE-2026-6973, Ivanti Endpoint Manager Mobile (EPMM): improper input validation ·
Added the same day
- CVE-2023-0266, Linux Kernel: use-after-free ·
- CVE-2022-42948, Fortra Cobalt Strike: user interface remote code execution ·
- CVE-2022-39197, Fortra Cobalt Strike: teamserver cross-site scripting (XSS) ·
- CVE-2022-38181, Arm Mali Graphics Processing Unit (GPU): mali GPU kernel driver use-after-free ·
- CVE-2022-3038, Chrome and other Chromium browsers: use-after-free ·
Every Apple flaw on CISA’s list · Everything added in March 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Apple iOS, iPadOS, and macOS Out-of-Bounds Write Vulnerability”. Known Exploited Vulnerabilities Catalog, added 30 Mar 2023.
- ^ National Institute of Standards and Technology. “CVE-2021-30900 Detail”. National Vulnerability Database, published 24 Aug 2021.
- ^ Apple. Advisories and fixes: support.apple.com, support.apple.com, support.apple.com, support.apple.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.052, percentile 92.5, 31 Oct 2026.
- CVE Program. “CVE-2021-30900”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.