A remote code execution vulnerability exists in the way that Microsoft browsers access objects in memory. The vulnerability could corrupt memory in a way that could allow an attacker to execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, the attacker could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
\nAn attacker could host a specially crafted website that is designed to exploit the vulnerability through Microsoft browsers, and then convince a user to view the website. The attacker could also take advantage of compromised websites, or websites that accept or host user-provided content or advertisements, by adding specially crafted content that could exploit the vulnerability. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically via an enticement in email or instant message, or by getting them to open an email attachment.
\nThe security update addresses the vulnerability by modifying how Microsoft browsers handle objects in memory.
","summary":"Microsoft Edge and Internet Explorer have a memory corruption bug that lets an attacker run code as the current user. CISA lists it as actively exploited and tags it as used in ransomware campaigns.","severity":"high","cvss":7.5,"epss":0.02696,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Microsoft Edge and Internet Explorer","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","internet-explorer","microsoft-edge","ransomware","vendor","windows"],"not_affected_if":["unknown"],"how_to_check":"Check which browser build is installed: Edge version under edge://settings/help and Internet Explorer via Help > About Internet Explorer. unknown for the affected version range.","fix":"Apply the Microsoft security update for Edge and Internet Explorer per vendor instructions (CISA required action). Specific fixed build: unknown.","status":"open","published_at":"2020-09-11T17:15:14+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:37:36+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-10-23T21:37:36Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft security update for Edge and Internet Explorer per vendor instructions (CISA required action). Specific fixed build: unknown.","reach":"internet","impact":"high","summary":"Microsoft Edge and Internet Explorer have a memory corruption bug that lets an attacker run code as the current user. CISA lists it as actively exploited and tags it as used in ransomware campaigns.","category":"vendor","who_cares":["windows","microsoft-edge","internet-explorer"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker runs code as the logged-in user after a crafted page load","analyst_note":"Find the affected and fixed build numbers in Microsoft's CVE-2020-0878 advisory (MSRC) and confirm whether Internet Explorer 11 on supported Windows is the main exposure.","how_to_check":"Check which browser build is installed: Edge version under edge://settings/help and Internet Explorer via Help > About Internet Explorer. unknown for the affected version range.","needs_analyst":true,"not_affected_if":["unknown"],"user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"high"},"cost_usd":0.000493,"input_tokens":2853,"output_tokens":416,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-0878':16A,19A '-2020':15A,18A 'accept':204C 'access':81C 'account':160C 'action':253C 'activ':59B 'add':214C 'address':275C 'administr':134C 'advantag':197C 'advertis':212C 'affect':144C 'allow':95C 'also':195C 'and':22A 'arbitrari':100C 'attach':271C 'attack':48B,97C,110C,138C,147C,166C,193C,228C,240C,245C 'attacker-control':239C 'browser':80C,182C,282C 'bug':44B 'campaign':68B 'case':225C 'chang':153C 'cisa':55B 'code':50B,71C,101C 'compromis':199C 'content':210C,217C,242C 'context':104C 'control':141C,241C 'convinc':185C,249C 'corrupt':12A,43B,88C 'could':87C,94C,116C,139C,148C,167C,194C,219C 'craft':171C,216C 'creat':158C 'current':53B,107C,124C,128C 'cve':14A,17A 'data':156C 'delet':155C 'design':175C 'edg':2A,7A,31B,36B 'edge':21A 'email':259C,270C 'entic':257C 'execut':72C,99C 'exist':74C 'exploit':25B,60B,113C,177C,220C 'explor':5A,10A,28B,39B 'explorer':24A 'forc':234C 'full':162C 'gain':117C 'get':265C 'handl':283C 'host':168C,206C 'howev':226C 'instal':150C 'instant':261C 'instead':243C 'internet':4A,9A,23A,27B,38B 'internet-explor':26B 'let':46B 'list':56B 'log':131C 'memori':11A,42B,84C,89C,286C 'messag':262C 'microsoft':1A,6A,20A,30B,35B,79C,181C,281C 'microsoft-edg':29B 'modifi':279C 'new':159C 'object':82C,284C 'open':268C 'program':151C 'provid':209C 'ransomwar':32B,67B 'remot':70C 'right':121C,136C,164C 'run':49B 'secur':273C 'special':170C,215C 'success':112C 'system':145C 'tag':62B 'take':140C,196C,252C 'typic':254C 'updat':274C 'use':65B 'user':54B,108C,120C,125C,129C,135C,163C,187C,208C,235C,250C 'user-provid':207C 'vendor':33B 'via':255C 'view':152C,189C,237C 'vulner':13A,73C,86C,115C,179C,222C,277C 'way':77C,92C,232C 'websit':172C,191C,200C,202C 'window':34B 'would':229C,246C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2020-09-11T17:15:14+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2020-0878","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-0878","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T12:39:25+00:00","note":null},{"source":"epss","external_id":"CVE-2020-0878","url":"https://api.first.org/data/v1/epss?cve=CVE-2020-0878","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2020-0878","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-0878","severity":null,"published_at":"2020-09-11T17:15:14+00:00","modified_at":"2026-06-17T02:46:53+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}