{"id":"CVE-2021-27878","kind":"vulnerability","aliases":["CVE-2021-27878"],"related":[],"title":"An issue was discovered in Veritas Backup Exec before 21.2","description":"An issue was discovered in Veritas Backup Exec before 21.2. The communication between a client and an Agent requires successful authentication, which is typically completed over a secure TLS communication. However, due to a vulnerability in the SHA Authentication scheme, an attacker is able to gain unauthorized access and complete the authentication process. Subsequently, the client can execute data management protocol commands on the authenticated connection. The attacker could use one of these commands to execute an arbitrary command on the system using system privileges.","summary":"Veritas Backup Exec Agent contains a command execution flaw in its data management protocol handling. An attacker can send a crafted protocol command to run arbitrary commands on the machine running the agent.","severity":"critical","cvss":9.0,"epss":null,"exploited":true,"exploited_at":"2023-04-07T00:00:00+00:00","products":[{"name":"Veritas Backup Exec Agent","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"veritas backup exec","fixed":["21.2"],"affected":"< 21.2","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["backup-exec","exploited","infrastructure","ransomware","veritas","windows"],"not_affected_if":["no-backup-exec-agent-installed"],"how_to_check":null,"fix":"Apply the updates per the vendor instructions (Veritas advisory not fetched; unknown which version is fixed).","status":"open","published_at":"2021-03-01T22:15:14+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:08:24+00:00","updated_at":"2026-10-23T22:29:04+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:08:24Z","model":"claude-haiku-5-5","output":{"fix":"Apply the updates per the vendor instructions (Veritas advisory not fetched; unknown which version is fixed).","reach":"network","impact":"high","summary":"Veritas Backup Exec Agent contains a command execution flaw in its data management protocol handling. An attacker can send a crafted protocol command to run arbitrary commands on the machine running the agent.","category":"infrastructure","who_cares":["veritas","backup-exec","windows"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker runs arbitrary commands on the backup agent machine.","analyst_note":"Find the Veritas advisory and the fixed Backup Exec Agent versions, plus a check for the agent version or exposed protocol port; CISA KEV lists it as exploited in ransomware campaigns.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-backup-exec-agent-installed"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000462,"input_tokens":2815,"output_tokens":361,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':12A,15A '-27878':13A,16A '21.2':10A,74C 'abl':108C 'access':112C 'agent':20A,35B,64B,82C 'arbitrari':57B,142C 'attack':48B,106C,132C 'authent':85C,103C,116C,129C 'backup':7A,18A,22A,25B,33B,71C 'backup-exec':24B 'client':79C,120C 'command':38B,54B,58B,126C,138C,143C 'communic':76C,94C 'complet':89C,114C 'connect':130C 'contain':36B 'could':133C 'craft':52B 'cve':11A,14A 'data':43B,123C 'discov':4A,68C 'due':96C 'exec':8A,19A,23A,26B,34B,72C 'execut':39B,122C,140C 'exploit':27B 'flaw':40B 'gain':110C 'handl':46B 'howev':95C 'infrastructur':28B 'issu':2A,66C 'machin':61B 'manag':44B,124C 'one':135C 'privileg':149C 'process':117C 'protocol':45B,53B,125C 'ransomwar':29B 'requir':83C 'run':56B,62B 'scheme':104C 'secur':92C 'send':50B 'sha':102C 'subsequ':118C 'success':84C 'system':146C,148C 'tls':93C 'typic':88C 'unauthor':111C 'use':134C,147C 'verita':6A,30B,32B,70C 'veritas':17A,21A 'vulner':99C 'window':31B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-03-01T22:15:14+00:00","kev":{"dateAdded":"2023-04-07","dueDate":"2023-04-28","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":"cve@mitre.org","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-27878","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27878","severity":null,"published_at":"2023-04-07T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T20:35:34+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-27878","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27878","severity":null,"published_at":"2021-03-01T22:15:14+00:00","modified_at":"2026-06-17T03:45:33+00:00","first_seen_at":"2026-10-23T22:29:04+00:00","fetched_at":"2026-10-23T22:29:04+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"}