---
id: "CVE-2026-85899"
kind: "vulnerability"
aliases: ["CVE-2026-85899"]
title: "Microsoft Edge: use-after-free lets an authorized user gain higher privileges"
severity: "high"
cvss: 8.1
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "Microsoft Edge (Chromium-based)", "fixed": ["155.0.4283.45"], "affected": "< 155.0.4283.45", "ecosystem": "vendor"}]
ecosystems: []
tags: ["browser", "chromium", "microsoft-edge", "other", "sandbox-escape", "windows"]
not_affected_if: []
published_at: "2026-10-29T16:19:45+00:00"
first_seen_at: "2026-10-29T16:26:01+00:00"
updated_at: "2026-10-29T16:34:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85899", "first_seen_at": "2026-10-29T16:26:01+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-29T16:34:56+00:00"}]
---

# Microsoft Edge: use-after-free lets an authorized user gain higher privileges

Use-after-free in Microsoft Edge (Chromium-based) lets an attacker who already runs code in Edge's sandbox (Low integrity) escape to Medium or High integrity. Microsoft rates it Important (CVSS 8.1), not exploited and not publicly disclosed, and fixed in 155.0.4283.45.

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

## Affected

- vendor:Microsoft Edge (Chromium-based) affected < 155.0.4283.45 fixed 155.0.4283.45

## How to check

Open edge://settings/help (or Edge menu > Help and feedback > About Microsoft Edge); versions below 155.0.4283.45 are affected. Fleet: Get-Item 'C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe' | % VersionInfo.

## Fix

Update Microsoft Edge (Chromium-based) to 155.0.4283.45 or later (edge://settings/help).

## Timeline

- 2026-10-29T16:26:01+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-85899
- 2026-10-29T16:34:56+00:00 analyst — Read MSRC advisory: fixed in Edge 155.0.4283.45 (released Oct 26 2026); not exploited, not publicly disclosed, 'Exploitation Unlikely'. OffSeq's 'public exploit' claim is just the CVSS E:P temporal metric, ignored. Sandbox-escape style EoP (Low IL to Medium/High IL).

## Documents

- [advisory] MSRC: CVE-2026-85899 Microsoft Edge (Chromium-based) Elevation of Privilege https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85899

## From the sources

Use after free in Microsoft Edge (Chromium-based) allows an authorized attacker to elevate privileges 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_