How severe is CVE-2020-16017?

CVE-2020-16017 has a CVSS score of 9.6/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-16017?

CVE-2020-16017 affects the following packages: CefSharp.Common (NuGet), CefSharp.Wpf (NuGet), CefSharp.WinForms (NuGet), CefSharp.Wpf.HwndHost (NuGet). Ecosystems affected: NuGet.

How do I fix CVE-2020-16017?

Update CefSharp.Common to version 86.0.241 or later. Run your dependency manager's update command and verify no transitive dependencies pin the vulnerable version. Use O3 Security's SCA scanner to confirm the fix is applied across your entire dependency tree.

Is CVE-2020-16017 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2020-16017, including 3 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-16017?

CVE-2020-16017 has an EPSS (Exploit Prediction Scoring System) score of 21.4%, placing it in the 96th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

Is CVE-2020-16017 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2020-16017 (Google Chrome Use-After-Free Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-05-03. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2020-16017?

CVE-2020-16017 is classified as Use After Free (CWE-416). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-16017 published, and has it been updated?

CVE-2020-16017 was published on January 8, 2021 and was last updated on March 14, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2021-11-03 — agencies required to remediate by 2022-05-03

.NET NuGet

CVE-2020-16017

CRITICAL

Use after free in CefSharp

Also known asGHSA-gvqv-779r-4jgp

Published

Jan 8, 2021

Updated

Mar 14, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

3 known

EPSS Exploitation Probability

via FIRST.org ↗

21.4%probability of exploitation in next 30 days

Moderate Risk96th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

4 pkgs affected

.NETCefSharp.Common.NETCefSharp.Wpf.NETCefSharp.WinForms.NETCefSharp.Wpf.HwndHost

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`CefSharp.Common`	all versions	86.0.241
.NETNuGet	`CefSharp.Wpf`	all versions	86.0.241
.NETNuGet	`CefSharp.WinForms`	all versions	86.0.241
.NETNuGet	`CefSharp.Wpf.HwndHost`	all versions	86.0.241

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Use after free in site isolation in Google Chrome prior to 86.0.4240.198…

chromereleases.googleblog.comChromeNov 2020

Use after free in site isolation in Google Chrome prior to 86.0.4240.198…

chromereleases.googleblog.comGoogle-sheetNov 2020

Use after free in site isolation in Google Chrome prior to 86.0.4240.198…

cisa.govCISAJul 2021

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-16017 in your stack?

O3 detects CVE-2020-16017 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works