---
id: "CVE-2026-85890"
kind: "vulnerability"
aliases: ["CVE-2026-85890"]
title: "Microsoft Edge: double free lets a web attacker run code"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "runtime"
products: [{"name": "Microsoft Edge (Chromium-based)", "fixed": ["154.0.4258.37", "155.0.4283.62"], "affected": "< 154.0.4258.37 (MSRC); update to 155.0.4283.62 or later", "ecosystem": "vendor"}]
ecosystems: []
tags: ["browser", "chromium", "linux", "macos", "microsoft-edge", "runtime", "windows"]
not_affected_if: ["patched-edge-155.0.4283.62"]
published_at: "2026-10-29T16:19:45+00:00"
first_seen_at: "2026-10-29T16:26:01+00:00"
updated_at: "2026-10-29T16:36:08+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85890", "first_seen_at": "2026-10-29T16:26:01+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-29T16:36:08+00:00"}]
---

# Microsoft Edge: double free lets a web attacker run code

Double free (CWE-415) in Microsoft Edge (Chromium-based) lets an attacker run code on the machine after a user opens a crafted web page or file. MSRC rates it Important, CVSS 8.8, not exploited, not publicly disclosed, 'Exploitation Less Likely'.

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

## Affected

- vendor:Microsoft Edge (Chromium-based) affected < 154.0.4258.37 (MSRC); update to 155.0.4283.62 or later fixed 154.0.4258.37, 155.0.4283.62

## How to check

Open edge://settings/help (Settings > About Microsoft Edge) and read the version. Treat anything older than 155.0.4283.62 (the Oct 16, 2026 Stable build) as exposed.

## Fix

Update Edge. MSRC lists build 154.0.4258.37 for this CVE; the Oct 16 2026 Stable release is 155.0.4283.62, and 156.0.4314.42 followed on Oct 22. Move to the latest Stable (at least 155.0.4283.62).

## Timeline

- 2026-10-29T16:26:01+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-85890
- 2026-10-29T16:36:08+00:00 analyst — Read MSRC page: double free, CVSS 8.8, not exploited, no PoC. MSRC build 154.0.4258.37 conflicts with Edge release notes (that build shipped Sept 24; Oct 16 Stable is 155.0.4283.62, cited by GovCERT.HK/Tenable), so fix text not verified; advise latest Stable. No mitigations found. No social search done (B tier, no PoC).

## Documents

- [advisory] MSRC: CVE-2026-85890 Edge (Chromium-based) RCE https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85890
- [fix] Microsoft Edge security release notes https://learn.microsoft.com/en-us/deployedge/microsoft-edge-relnotes-security

## From the sources

Double free in Microsoft Edge (Chromium-based) allows an unauthorized attacker to execute code over a network.

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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_