---
id: "CVE-2021-27085"
kind: "vulnerability"
aliases: ["CVE-2021-27085"]
title: "Microsoft Internet Explorer: Microsoft Internet Explorer Remote Code Execution Vulnerability"
severity: "high"
cvss: 8.8
epss: 0.05448
exploited: true
status: "open"
category: "other"
products: [{"name": "Microsoft Internet Explorer", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "internet-explorer", "other", "windows"]
not_affected_if: ["internet-explorer-removed"]
published_at: "2021-03-11T16:15:18+00:00"
first_seen_at: "2026-10-23T19:11:53+00:00"
updated_at: "2026-10-23T21:57:34+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27085", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-27085", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-27085", "first_seen_at": "2026-10-23T21:57:34+00:00"}]
---

# Microsoft Internet Explorer: Microsoft Internet Explorer Remote Code Execution Vulnerability

Microsoft Internet Explorer contains an unspecified flaw that lets an attacker run code remotely. CISA lists it as actively exploited in the wild.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Internet Explorer affected ? fixed ?

## Fix

Apply updates per vendor instructions, as CISA requires; the sources do not name the fixed version.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27085
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2021-27085
- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-27085

## From the sources

Microsoft Internet Explorer contains an unspecified vulnerability that allows for remote code execution.

CISA required action: Apply updates per vendor instructions.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_