What is CVE-2021-43221?

CVE-2021-43221 is a medium-severity vulnerability in Microsoft Edge Chromium, classified under Code Injection. CVSS score: 4.2/10. Published 2021-11-24.

How severe is CVE-2021-43221?

Medium severity. CVSS v3 base score is 4.2 out of 10.

RCE in Microsoft Edge Chromium

CVE-2021-43221

Microsoft Edge (Chromium-based) Remote Code Execution Vulnerability

Vulnerability class: RCE (Remote Code Execution)

Published 2021-11-24 · last modified 2026-08-19.

CVSS v3 metric

CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.011 (65.7th percentile), scored 2026-10-08.

Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 65.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: +0.001

Affected products

Microsoft Edge Chromium
Microsoft Edge (Chromium-Based) — versions 1.0.0

Weakness classification (CWE)

CWE-94 — Code Injection

References

af854a3a-2127-422b-91ae-364da2661108 (Patch, Vendor Advisory)
msrc.microsoft.com/update-guide/vulnerability/CVE-2021-43221 (vendor-advisory, patch)

Frequently asked questions

What is CVE-2021-43221?: CVE-2021-43221 is a medium-severity vulnerability in Microsoft Edge Chromium, classified under Code Injection. CVSS score: 4.2/10. Published 2021-11-24.
How severe is CVE-2021-43221?: Medium severity. CVSS v3 base score is 4.2 out of 10.