{"id":"CVE-2026-85890","kind":"vulnerability","aliases":["CVE-2026-85890"],"related":[],"title":"Microsoft Edge: double free lets a web attacker run code","description":"Double free in Microsoft Edge (Chromium-based) allows an unauthorized attacker to execute code over a network.","summary":"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'.","severity":"high","cvss":8.8,"epss":null,"exploited":false,"exploited_at":null,"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"],"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).","status":"open","published_at":"2026-10-29T16:19:45+00:00","first_seen_at":"2026-10-29T16:26:01+00:00","triaged_at":"2026-10-29T16:27:59+00:00","updated_at":"2026-10-29T16:36:08+00:00","category":"runtime","confidence":0.8,"triage":{"at":"2026-10-29T16:27:59Z","model":"claude-haiku-5-5","output":{"fix":"- unknown","reach":"internet","title":"Microsoft Edge: double free lets a web attacker run code","impact":"high","summary":"A double free bug in the Chromium-based Microsoft Edge browser can be triggered over a network. An unauthorized attacker may be able to execute code on the affected machine.","audience":"everyone","category":"runtime","nicknames":[],"who_cares":["microsoft-edge","chromium","windows","macos"],"confidence":0.5,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker runs code on the victim's computer over the network","analyst_note":"Check the Microsoft Security Response Center entry for CVE-2026-85890 for affected versions and the fixed build; the NVD entry gives only the description and CVSS 8.8.","how_to_check":"- Open Edge and check the version under Settings > About Microsoft Edge.\n- unknown","plain_action":"Update Microsoft Edge to the newest version available from its About page.","needs_analyst":true,"not_affected_if":[],"who_is_affected":"Anyone running a Chromium-based Microsoft Edge build that has not received the fix. The sources do not name the affected version range, and say nothing about required configuration or user interaction.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.00064,"input_tokens":4064,"output_tokens":468,"severity_before":"high"},"analyst_status":"done","analyst_note":"Check the Microsoft Security Response Center entry for CVE-2026-85890 for affected versions and the fixed build; the NVD entry gives only the description and CVSS 8.8.","search":"'-2026':12A,15A '-415':34B '-85890':13A,16A '8.8':64B 'allow':81C 'attack':8A,43B,84C 'base':40B,80C 'based':21A 'browser':22B 'chromium':20A,23B,39B,79C 'chromium-bas':38B,78C 'chromium-based':19A 'code':10A,45B,87C 'craft':54B 'cve':11A,14A 'cvss':63B 'cwe':33B 'disclos':69B 'doubl':3A,31B,73C 'edg':2A,28B,37B,77C 'edge':18A 'execut':86C 'exploit':66B,70B 'file':58B 'free':4A,32B,74C 'import':62B 'less':71B 'let':5A,41B 'like':72B 'linux':24B 'machin':48B 'maco':25B 'microsoft':1A,17A,27B,36B,76C 'microsoft-edg':26B 'msrc':59B 'network':90C 'open':52B 'page':56B 'public':68B 'rate':60B 'run':9A,44B 'runtim':29B 'unauthor':83C 'user':51B 'web':7A,55B 'window':30B","nicknames":[],"mitigations":[],"who_affected":"Anyone running Microsoft Edge (Chromium-based) on desktop below the fixed build. Exploitation needs a user to open attacker-controlled content, so machines where people browse the open web are most at risk. Machines without Edge, or with Edge already updated, can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"everyone","plain_action":"Update Microsoft Edge: open Edge, go to Settings > About Microsoft Edge, and let it install the update, then restart the browser.","first_public_at":"2026-10-29T16:19:45+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-2026-85890","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-85890","severity":null,"published_at":"2026-10-29T16:19:45+00:00","modified_at":"2026-10-29T16:19:45+00:00","first_seen_at":"2026-10-29T16:26:01+00:00","fetched_at":"2026-10-29T16:26:01+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-85890:1068","url":null,"severity":null,"published_at":"2026-10-29T16:36:08+00:00","modified_at":"2026-10-29T16:36:08+00:00","first_seen_at":"2026-10-29T16:36:08+00:00","fetched_at":"2026-10-29T16:36:08+00:00","note":"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":[{"id":17789,"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85890","title":"MSRC: CVE-2026-85890 Edge (Chromium-based) RCE","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}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}