# CVE-2021-1870: Apple iOS, iPadOS, and macOS WebKit Remote Code Execution

> A logic issue in Apple operating systems allows remote attackers to execute arbitrary code, with evidence of active exploitation.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Apr 2021
- **Updated:** 21 Oct 2025
- **Also known as:** DEBIAN-CVE-2021-1870, GHSA-f8fh-g8mv-p7hh, UBUNTU-CVE-2021-1870

## What is CVE-2021-1870?

CVE-2021-1870 is a critical vulnerability in Apple Ipados, published on 2 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

## Which versions are affected by CVE-2021-1870?

It affects 6 products.


Products: Apple Ipados, Apple Iphone Os, Apple Mac Os X, Apple Macos, Fedoraproject Fedora, Webkitgtk Webkitgtk.

## How do I fix CVE-2021-1870?

Apply the vendor's patch. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-1870 being exploited?

Yes. Attackers have exploited CVE-2021-1870 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-2021-1870 and fix it if it is affected.

What it is: CVE-2021-1870 is a critical vulnerability in Apple Ipados, published on 2 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2021-1870 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-2021-1870/ (Markdown: https://insights.sbomify.com/CVE-2021-1870/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1870
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1870
- OSV: https://osv.dev/vulnerability/CVE-2021-1870

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1870/
Summaries are generated and may contain mistakes; the official description above is the record.