CVE-2021-30983
CVE-2021-30983 is a security flaw in Apple iOS and iPadOS, the operating system on iPhones and iPads. Attackers can run their own code on Apple iOS and iPadOS. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 27 Jun 2022.[1]
Apple iOS and iPadOS 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 15.2 of iOS and iPadOS.
Description
CISA calls it a buffer overflow in Apple iOS and iPadOS. In its words: “Apple iOS and iPadOS contain a buffer overflow vulnerability that could allow an application to execute code with kernel privileges.”[1]
The CVE record adds: “A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 15.2 and iPadOS 15.2. An application may be able to execute arbitrary code with kernel privileges.”[2]
The underlying weakness is memory buffer error (CWE-119), 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 one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| iOS and iPadOS | 15.2 |
Every device with Apple iOS and iPadOS needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 27 Jun 2022, 307 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 18 Jul 2022 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 3%. That’s in the top 13% 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 and iPadOS 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 15.2 or later.Fixed in version 15.2 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 3%.[4] |
See also
Other Apple iOS and iPadOS flaws
- CVE-2023-41974: use-after-free ·
- CVE-2025-24200: incorrect authorization ·
- CVE-2023-42824: kernel privilege escalation ·
- CVE-2022-42827: out-of-bounds write ·
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 memory buffer error flaws
- CVE-2026-88779, Citrix NetScaler: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88772, Citrix NetScaler: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88771, Citrix NetScaler: improper input validation ·
- CVE-2026-8452, Citrix NetScaler ADC and NetScaler Gateway: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2009-3459, Adobe Acrobat and Reader: heap-based buffer overflow ·
Added the same day
- CVE-2022-29499, Mitel MiVoice Connect: data validation ·
- CVE-2021-4034, Red Hat Polkit: out-of-bounds read and write ·
- CVE-2021-30533, Chrome and other Chromium browsers: security bypass ·
- CVE-2020-9907, Apple devices: memory corruption ·
- CVE-2020-3837, Apple devices: memory corruption ·
Every Apple flaw on CISA’s list · Everything added in June 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Apple iOS and iPadOS Buffer Overflow Vulnerability”. Known Exploited Vulnerabilities Catalog, added 27 Jun 2022.
- ^ National Institute of Standards and Technology. “CVE-2021-30983 Detail”. National Vulnerability Database, published 24 Aug 2021.
- ^ Apple. Advisories and fixes: support.apple.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.029, percentile 87.1, 31 Oct 2026.
- CVE Program. “CVE-2021-30983”. 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.