# CVE-2020-16017: Google Chrome Use-After-Free

> A remote attacker with compromised renderer access can escape the sandbox via a crafted HTML page due to a use-after-free bug in Chrome.

- **Severity:** Critical 9.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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 Jan 2021
- **Updated:** 21 Oct 2025
- **Also known as:** DEBIAN-CVE-2020-16017, GHSA-gvqv-779r-4jgp, UBUNTU-CVE-2020-16017

## What is CVE-2020-16017?

CVE-2020-16017 is a critical use after free vulnerability in Google Chrome, published on 8 Jan 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

Use after free in site isolation in Google Chrome prior to 86.0.4240.198 allowed a remote attacker who had compromised the renderer process to potentially perform a sandbox escape via a crafted HTML page.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2020-16017?

8 open source packages ship an affected version, including CefSharp.Common, CefSharp.WinForms and CefSharp.Wpf. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `CefSharp.Common` | NuGet | All versions | 86.0.241 |
| `CefSharp.Common` | NuGet | All versions | 86.0.241 |
| `CefSharp.WinForms` | NuGet | All versions | 86.0.241 |
| `CefSharp.WinForms` | NuGet | All versions | 86.0.241 |
| `CefSharp.Wpf` | NuGet | All versions | 86.0.241 |
| `CefSharp.Wpf` | NuGet | All versions | 86.0.241 |
| `CefSharp.Wpf.HwndHost` | NuGet | All versions | 86.0.241 |
| `CefSharp.Wpf.HwndHost` | NuGet | All versions | 86.0.241 |

Products: Google Chrome.

## How do I fix CVE-2020-16017?

Upgrade CefSharp.Common to 86.0.241 or later. US federal agencies must fix it by 3 May 2022.

## Is CVE-2020-16017 being exploited?

Yes. Attackers have exploited CVE-2020-16017 in the wild since at least 3 Nov 2021.

## Other vulnerabilities in Google Chrome

- [CVE-2022-4135](https://insights.sbomify.com/CVE-2022-4135/): Google Chromium GPU Heap Buffer Overflow (critical 9.6, exploited in the wild)
- [CVE-2020-16010](https://insights.sbomify.com/CVE-2020-16010/): Google Chrome for Android UI Heap Buffer Overflow (critical 9.6, exploited in the wild)
- [CVE-2026-87491](https://insights.sbomify.com/CVE-2026-87491/): Google Chromium V8 Out of Bounds Write (high 8.8, exploited in the wild)
- [CVE-2026-85046](https://insights.sbomify.com/CVE-2026-85046/): Google Chromium V8 Type Confusion (high 8.8, exploited in the wild)
- [CVE-2026-11645](https://insights.sbomify.com/CVE-2026-11645/): Google Chromium V8 Out-of-Bounds Read and Write (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-16017 and fix it if it is affected.

What it is: CVE-2020-16017 is a critical use after free vulnerability in Google Chrome, published on 8 Jan 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-2020-16017 in the wild since at least 3 Nov 2021.

Affected packages and fixed versions:
- CefSharp.Common (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.Common (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.WinForms (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.WinForms (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.Wpf (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.Wpf (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.Wpf.HwndHost (NuGet): affected all versions; fixed in 86.0.241
- CefSharp.Wpf.HwndHost (NuGet): affected all versions; fixed in 86.0.241

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-2020-16017/ (Markdown: https://insights.sbomify.com/CVE-2020-16017/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-16017
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-16017
- OSV: https://osv.dev/vulnerability/CVE-2020-16017

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-16017/
Summaries are generated and may contain mistakes; the official description above is the record.