{"id":"CVE-2021-27104","published":"2021-02-16T21:15:13Z","modified":"2026-06-17T03:44:18Z","title":"Accellion FTA OS Command Injection Vulnerability","vendor":"Accellion","product":"FTA","tier":"core","eol":null,"description":{"text":"Accellion FTA 9_12_370 and earlier is affected by OS command execution via a crafted POST request to various admin endpoints. The fixed version is FTA_9_12_380 and later.","provenance":"source","from":"NVD"},"summary":{"text":"Accellion's FTA product contains an OS command injection flaw in its admin endpoints, affecting FTA 9_12_370 and earlier, and fixed in FTA_9_12_380 and later. An unauthenticated remote attacker who can reach those endpoints can send a crafted POST request to execute operating system commands on the server, with no user interaction required.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T08:32:01Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.56686,"percentile":0.99059,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":true,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-27104","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-04-13","exploitedFirstSeen":"2021-04-13","ransomware":true,"evidence":[{"url":"https://unit42.paloaltonetworks.com/clop-ransomware/","date":"2021-04-13"},{"url":"https://www.trendmicro.com/vinfo/us/security/news/cybercrime-and-digital-threats/ransomware-double-extortion-and-beyond-revil-clop-and-conti","date":"2021-06-15"},{"url":"https://cisa.gov/news-events/cybersecurity-advisories/aa21-055a","date":"2021-06-17"},{"url":"https://www.cisa.gov/news-events/cybersecurity-advisories/aa21-209a","date":"2021-08-20"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"},{"url":"https://cybersecurityworks.com/howdymanage/uploads/file/ransomware-_-2022-spotlight-report_compressed.pdf","date":"2022-01-26"},{"url":"https://www.paloaltonetworks.com/content/dam/pan/en_US/assets/pdf/reports/2022-unit42-ransomware-threat-report-final.pdf","date":"2022-03-24"},{"url":"https://cisa.gov/news-events/alerts/2022/04/27/2021-top-routinely-exploited-vulnerabilities","date":"2022-04-28"},{"url":"https://cisa.gov/news-events/cybersecurity-advisories/aa22-117a","date":"2022-04-28"},{"url":"https://static.tenable.com/marketing/whitepapers/Whitepaper-Ransomware_Ecosystem.pdf","date":"2022-06-22"}],"evidenceTotal":24,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-78","name":"Improper Neutralization of Special Elements used in an OS Command"},{"id":"CWE-20","name":"Improper Input Validation"}],"references":[{"url":"https://github.com/accellion/CVEs/blob/main/CVE-2021-27104.txt","tags":["Broken Link","Third Party Advisory"]},{"url":"https://www.accellion.com/products/fta/","tags":["Product","Vendor Advisory"]},{"url":"https://github.com/accellion/CVEs/blob/main/CVE-2021-27104.txt","tags":["Broken Link","Third Party Advisory"]},{"url":"https://www.accellion.com/products/fta/","tags":["Product","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27104","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Command Injection","mappingType":"exploitation_technique","evidence":[],"comment":"CVE-2021-27104 is an operating system command injection vulnerability in Accellion File Transfer Appliance in that allows an adversary to execute commands by sending a specially crafted POST request to the product's administrative endpoint.","confidence":"high"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Command Injection","mappingType":"primary_impact","evidence":[],"comment":"CVE-2021-27104 is an operating system command injection vulnerability in Accellion File Transfer Appliance in that allows an adversary to execute commands by sending a specially crafted POST request to the product's administrative endpoint.","confidence":"high"},{"id":"T1005","name":"Data from Local System","tactics":["collection"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Command Injection","mappingType":"secondary_impact","evidence":[],"comment":"CVE-2021-27104 is an operating system command injection vulnerability in Accellion File Transfer Appliance in that allows an adversary to execute commands by sending a specially crafted POST request to the product's administrative endpoint.","confidence":"high"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-13874","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-13874","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"source"},{"stage":"primary","techniques":["T1059"],"provenance":"source"},{"stage":"secondary","techniques":["T1005"],"provenance":"source"}],"timeline":[{"date":"2021-02-16","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27104","provenance":"source"},{"date":"2021-04-13","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://unit42.paloaltonetworks.com/clop-ransomware/","provenance":"source"},{"date":"2021-11-03","kind":"kev","label":"Added to CISA KEV (known ransomware use)","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2021-11-03","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-13874","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":260},"priority":{"score":74.7,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 2025 days ago"},{"name":"Known ransomware use","points":10.0,"detail":"CISA KEV and VulnCheck KEV: Known"},{"name":"EPSS percentile","points":19.81,"detail":"percentile 0.9906"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":6.86,"detail":"base score 9.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}