{"id":"CVE-2021-27104","kind":"vulnerability","aliases":["CVE-2021-27104"],"related":[],"title":"Accellion FTA: Accellion FTA OS Command Injection Vulnerability","description":"Accellion FTA contains an OS command injection vulnerability exploited via a crafted POST request to various admin endpoints.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Accellion File Transfer Appliance (FTA) has an OS command injection flaw in its admin endpoints. An unauthenticated attacker who sends a crafted POST request can run operating system commands on the appliance.","severity":"critical","cvss":10.0,"epss":0.56686,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"Accellion FTA","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["accellion-fta","exploited","file-transfer","ransomware","self-hosted","vendor"],"not_affected_if":["not-running-fta"],"how_to_check":null,"fix":"Apply the updates per the vendor instructions (CISA required action); exact fixed version unknown from sources.","status":"open","published_at":"2021-02-16T21:15:13+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:32:02+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-10-23T21:32:02Z","model":"claude-haiku-5-5","output":{"fix":"Apply the updates per the vendor instructions (CISA required action); exact fixed version unknown from sources.","reach":"internet","impact":"high","summary":"Accellion File Transfer Appliance (FTA) has an OS command injection flaw in its admin endpoints. An unauthenticated attacker who sends a crafted POST request can run operating system commands on the appliance.","category":"vendor","who_cares":["accellion-fta","self-hosted","file-transfer"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker runs OS commands on the appliance and can reach stored files","analyst_note":"Find the vendor advisory and fixed FTA versions, plus indicators of compromise, to fill how_to_check and fix; confirm auth requirement from the vendor advisory.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["not-running-fta"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000458,"input_tokens":2819,"output_tokens":353,"severity_before":"unknown"},"analyst_status":"queued","analyst_note":"Find the vendor advisory and fixed FTA versions, plus indicators of compromise, to fill how_to_check and fix; confirm auth requirement from the vendor advisory.","search":"'-2021':10A,13A '-27104':11A,14A 'accellion':1A,3A,15A,18B,29B,61C 'accellion-fta':17B 'action':81C 'admin':42B,77C 'appli':82C 'applianc':32B,60B 'attack':46B 'cisa':79C 'command':6A,37B,57B,66C 'contain':63C 'craft':50B,72C 'cve':9A,12A 'endpoint':43B,78C 'exploit':20B,69C 'file':22B,30B 'file-transf':21B 'flaw':39B 'fta':2A,4A,16A,19B,33B,62C 'host':27B 'inject':7A,38B,67C 'instruct':86C 'oper':55B 'os':5A,36B,65C 'per':84C 'post':51B,73C 'ransomwar':24B 'request':52B,74C 'requir':80C 'run':54B 'self':26B 'self-host':25B 'send':48B 'system':56B 'transfer':23B,31B 'unauthent':45B 'updat':83C 'various':76C 'vendor':28B,85C 'via':70C 'vulner':8A,68C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-02-16T21:15:13+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-27104","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27104","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":"2026-10-25T13:39:32+00:00","note":null},{"source":"epss","external_id":"CVE-2021-27104","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-27104","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-2021-27104","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27104","severity":null,"published_at":"2021-02-16T21:15:13+00:00","modified_at":"2026-06-17T03:44:18+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"}