{"id":"CVE-2026-96203","kind":"vulnerability","aliases":["CVE-2026-96203"],"related":[],"title":"Microsoft Edge: use-after-free lets a network attacker gain higher privileges","description":"Use after free in Microsoft Edge (Chromium-based) allows an unauthorized attacker to elevate privileges over a network.","summary":"A use-after-free bug in Microsoft Edge (Chromium-based) lets an unauthorized attacker elevate privileges over a network. The sources give no further detail on the trigger or the exact privilege gained.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"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","use-after-free","windows"],"not_affected_if":["patched-edge-155.0.4283.45"],"how_to_check":"Edge menu > Help and feedback > About Microsoft Edge; vulnerable if the version is below 155.0.4283.45. Check by command: msedge --version or (Get-Item 'C:\\Program Files (x86)\\Microsoft\\Edge\\Application\\msedge.exe').VersionInfo.ProductVersion","fix":"Update Microsoft Edge (Chromium-based) to 155.0.4283.45 or later (per MSRC mirror; confirm on the MSRC page). Current Stable is 156.0.4314.42.","status":"open","published_at":"2026-10-29T16:20:09+00:00","first_seen_at":"2026-10-29T16:26:04+00:00","triaged_at":"2026-10-29T16:27:52+00:00","updated_at":"2026-10-29T16:33:51+00:00","category":"other","confidence":0.6,"triage":{"at":"2026-10-29T16:27:52Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Microsoft Edge: use-after-free lets a network attacker gain higher privileges","impact":"high","summary":"A use-after-free bug in Microsoft Edge (Chromium-based) lets an unauthorized attacker elevate privileges over a network. The sources give no further detail on the trigger or the exact privilege gained.","audience":"everyone","category":"other","nicknames":[],"who_cares":["microsoft-edge","chromium","windows"],"confidence":0.4,"fix_status":"unknown","needs_auth":"unknown","worst_case":"attacker elevates privileges over the network","analyst_note":"Check the Microsoft Security Response Center entry for CVE-2026-96203 for affected versions, fixed build, and whether user interaction is needed.","how_to_check":"- Check the installed Edge version (Edge menu > Help and feedback > About Microsoft Edge), since the sources do not name affected version ranges\n- unknown","plain_action":"Update Microsoft Edge to the latest version, using the browser's About Microsoft Edge page to install any available update.","needs_analyst":true,"not_affected_if":[],"who_is_affected":"unknown","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000634,"input_tokens":4072,"output_tokens":453,"severity_before":"high"},"analyst_status":"done","analyst_note":"Check the Microsoft Security Response Center entry for CVE-2026-96203 for affected versions, fixed build, and whether user interaction is needed.","search":"'-2026':15A,18A '-96203':16A,19A 'allow':80C 'attack':10A,51B,83C 'base':47B,79C 'based':24A 'browser':25B 'bug':41B 'chromium':23A,26B,46B,78C 'chromium-bas':45B,77C 'chromium-based':22A 'cve':14A,17A 'detail':62B 'edg':2A,29B,44B,76C 'edge':21A 'elev':52B,85C 'exact':68B 'free':6A,34B,40B,73C 'gain':11A,70B 'give':59B 'higher':12A 'let':7A,48B 'microsoft':1A,20A,28B,43B,75C 'microsoft-edg':27B 'network':9A,56B,89C 'privileg':13A,53B,69B,86C 'sourc':58B 'trigger':65B 'unauthor':50B,82C 'use':4A,32B,38B,71C 'use-after-fre':3A,31B,37B 'window':35B","nicknames":[],"mitigations":[],"who_affected":"Anyone running Microsoft Edge (Chromium-based) older than 155.0.4283.45 is exposed; the attack comes over the network and needs the user to visit or open attacker content (user interaction required). Desktop users and managed fleets that pin or delay Edge updates matter most. Machines already auto-updated to Edge 155.0.4283.45 or newer can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update Microsoft Edge: open the menu, choose Help and feedback > About Microsoft Edge, and restart the browser when it finishes updating.","first_public_at":"2026-10-29T16:20:09+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-96203","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-96203","severity":null,"published_at":"2026-10-29T16:20:09+00:00","modified_at":"2026-10-29T16:20:09+00:00","first_seen_at":"2026-10-29T16:26:04+00:00","fetched_at":"2026-10-29T16:26:04+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-96203:1060","url":null,"severity":null,"published_at":"2026-10-29T16:33:51+00:00","modified_at":"2026-10-29T16:33:51+00:00","first_seen_at":"2026-10-29T16:33:51+00:00","fetched_at":"2026-10-29T16:33:51+00:00","note":"MSRC page is JS-rendered and unreadable to me; fixed build 155.0.4283.45 comes from an MSRC mirror (EchelonGraph) and OffSeq, not confirmed on a vendor page, so nothing marked verified. Edge release notes list 155.0.4283.45 as Stable on Oct 8 (later stable 156.0.4314.42 Oct 22) but do not list this CVE. CVSS 8.8 needs user interaction (UI:R). No exploitation or PoC found; no X search done."}],"documents":[{"id":17762,"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-96203","title":"MSRC Security Update Guide: CVE-2026-96203 (page is JS-rendered, text not readable)","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":17760,"url":"https://learn.microsoft.com/en-us/deployedge/microsoft-edge-relnotes-security","title":"Microsoft Edge security release notes","kind":"release","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"fix","confidence":null,"note":null},{"id":17764,"url":"https://echelongraph.io/pulse/vendor-advisories/microsoft/CVE-2026-96203","title":"EchelonGraph mirror of MSRC entry (fixed build 155.0.4283.45)","kind":"other","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"mentions","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}