# CVE-2021-30761: Apple iOS WebKit Memory Corruption

> Attackers can execute arbitrary code on iOS devices by tricking users into visiting malicious web content, requiring immediate patching.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/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:** Over the internet
- **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-2021-30761, GHSA-6qp6-2ggr-xv6x, UBUNTU-CVE-2021-30761

## What is CVE-2021-30761?

CVE-2021-30761 is a high-severity memory corruption vulnerability in Apple Iphone Os, published on 8 Sep 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A memory corruption issue was addressed with improved state management. This issue is fixed in iOS 12.5.4. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-30761?

It affects 1 product.


Products: Apple Iphone Os.

## How do I fix CVE-2021-30761?

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

## Is CVE-2021-30761 being exploited?

Yes. Attackers have exploited CVE-2021-30761 in the wild since at least 3 Nov 2021.

## Other vulnerabilities in Apple Iphone Os

- [CVE-2021-30666](https://insights.sbomify.com/CVE-2021-30666/): Apple iOS WebKit Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2021-30762](https://insights.sbomify.com/CVE-2021-30762/): Apple iOS WebKit Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2016-4657](https://insights.sbomify.com/CVE-2016-4657/): Apple iOS Webkit Memory Corruption (high 8.8, exploited in the wild)
- [CVE-2019-7286](https://insights.sbomify.com/CVE-2019-7286/): Apple Multiple Products Memory Corruption (high 7.8, exploited in the wild)
- [CVE-2019-7287](https://insights.sbomify.com/CVE-2019-7287/): Apple iOS Memory Corruption (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-30761 and fix it if it is affected.

What it is: CVE-2021-30761 is a high-severity memory corruption vulnerability in Apple Iphone Os, published on 8 Sep 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: Yes. Attackers have exploited CVE-2021-30761 in the wild since at least 3 Nov 2021.

Affected product: Apple Iphone Os. 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-2021-30761/ (Markdown: https://insights.sbomify.com/CVE-2021-30761/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-30761
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-30761
- OSV: https://osv.dev/vulnerability/CVE-2021-30761

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-30761/
Summaries are generated and may contain mistakes; the official description above is the record.