{"id":"CVE-2020-0688","kind":"vulnerability","aliases":["CVE-2020-0688"],"related":[],"title":"Microsoft Exchange Server: Microsoft Exchange Server Validation Key Remote Code Execution Vulnerability","description":"A remote code execution vulnerability exists in Microsoft Exchange software when the software fails to properly handle objects in memory, aka 'Microsoft Exchange Memory Corruption Vulnerability'.","summary":"Microsoft Exchange Server installs with a static validation key shared across installations, so an attacker who knows the key can forge the ViewState data the server trusts. This lets an authenticated attacker run code on the Exchange server.","severity":"critical","cvss":9.0,"epss":0.99962,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Microsoft Exchange Server","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exchange-server","exploited","on-premises","ransomware","vendor","windows"],"not_affected_if":["exchange-online","patched-server"],"how_to_check":null,"fix":"Apply the Microsoft update for CVE-2020-0688 per vendor instructions (CISA KEV required action); the specific build number is not in the sources.","status":"open","published_at":"2020-02-11T22:15:15+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:37:24+00:00","updated_at":"2026-10-23T21:57:34+00:00","category":"vendor","confidence":0.8,"triage":{"at":"2026-10-23T21:37:24Z","model":"claude-haiku-5-5","output":{"fix":"Apply the Microsoft update for CVE-2020-0688 per vendor instructions (CISA KEV required action); the specific build number is not in the sources.","reach":"network","impact":"high","summary":"Microsoft Exchange Server installs with a static validation key shared across installations, so an attacker who knows the key can forge the ViewState data the server trusts. This lets an authenticated attacker run code on the Exchange server.","category":"vendor","who_cares":["exchange-server","on-premises","windows"],"confidence":0.8,"needs_auth":"yes","worst_case":"Attacker runs code as SYSTEM on the Exchange server","analyst_note":"Need the exact patched build numbers and a verification method from Microsoft's advisory for CVE-2020-0688 (msrc.microsoft.com) and CISA KEV guidance.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["exchange-online","patched-server"],"user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"critical"},"cost_usd":0.000467,"input_tokens":2837,"output_tokens":366,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Need the exact patched build numbers and a verification method from Microsoft's advisory for CVE-2020-0688 (msrc.microsoft.com) and CISA KEV guidance.","search":"'-0688':15A,18A '-2020':14A,17A 'across':42B 'aka':90C 'attack':46B,63B 'authent':62B 'code':10A,65B,72C 'corrupt':94C 'cve':13A,16A 'data':55B 'exchang':2A,5A,23B,33B,68B,78C,92C 'exchange':20A 'exchange-serv':22B 'execut':11A,73C 'exist':75C 'exploit':25B 'fail':83C 'forg':52B 'handl':86C 'instal':35B,43B 'key':8A,40B,50B 'know':48B 'let':60B 'memori':89C,93C 'microsoft':1A,4A,19A,32B,77C,91C 'object':87C 'on-premis':26B 'premis':28B 'proper':85C 'ransomwar':29B 'remot':9A,71C 'run':64B 'server':3A,6A,21A,24B,34B,57B,69B 'share':41B 'softwar':79C,82C 'static':38B 'trust':58B 'valid':7A,39B 'vendor':30B 'viewstat':54B 'vulner':12A,74C,95C 'window':31B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2020-02-11T22:15:15+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:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2020-0688","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-0688","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-2020-0688","url":"https://api.first.org/data/v1/epss?cve=CVE-2020-0688","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-2020-0688","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-0688","severity":null,"published_at":"2020-02-11T22:15:15+00:00","modified_at":"2026-06-17T02:46:21+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","fetched_at":"2026-10-23T21:57:34+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"}