# CVE-2021-30663: Apple Multiple Products WebKit Integer Overflow

> Processing maliciously crafted web content may lead to arbitrary code execution due to an integer overflow in WebKit.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 8 Sep 2021
- **Updated:** 21 Oct 2025
- **Also known as:** DEBIAN-CVE-2021-30663, GHSA-5g93-pf3w-6f59, UBUNTU-CVE-2021-30663

## What is CVE-2021-30663?

CVE-2021-30663 is a high-severity vulnerability in Apple Ipados, published on 8 Sep 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2021-30663?

It affects 5 products.


Products: Apple Ipados, Apple Iphone Os, Apple Macos, Apple Safari, Apple Tvos.

## How do I fix CVE-2021-30663?

Upgrade to a fixed version. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-30663 being exploited?

Yes. Attackers have exploited CVE-2021-30663 in the wild since at least 3 Nov 2021.

## Other vulnerabilities in Apple Ipados

- [CVE-2025-43300](https://insights.sbomify.com/CVE-2025-43300/): Apple iOS, iPadOS, and macOS Out-of-Bounds Write (critical 10.0, exploited in the wild)
- [CVE-2025-24201](https://insights.sbomify.com/CVE-2025-24201/): Apple Multiple Products WebKit Out-of-Bounds Write (critical 10.0, exploited in the wild)
- [CVE-2025-24085](https://insights.sbomify.com/CVE-2025-24085/): Apple Multiple Products Use-After-Free (critical 10.0, exploited in the wild)
- [CVE-2025-31200](https://insights.sbomify.com/CVE-2025-31200/): Apple Multiple Products Memory Corruption (critical 9.8, exploited in the wild)
- [CVE-2025-31201](https://insights.sbomify.com/CVE-2025-31201/): Apple Multiple Products Arbitrary Read and Write (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-30663 and fix it if it is affected.

What it is: CVE-2021-30663 is a high-severity vulnerability in Apple Ipados, published on 8 Sep 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: Yes. Attackers have exploited CVE-2021-30663 in the wild since at least 3 Nov 2021.

Affected product: Apple Ipados. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-30663/ (Markdown: https://insights.sbomify.com/CVE-2021-30663/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-30663
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-30663
- OSV: https://osv.dev/vulnerability/CVE-2021-30663

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-30663/
Summaries are generated and may contain mistakes; the official description above is the record.