{"id":"CVE-2021-27876","kind":"vulnerability","aliases":["CVE-2021-27876"],"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. By using crafted input parameters in one of these commands, an attacker can access an arbitrary file on the system using System privileges.","summary":"Veritas Backup Exec Agent has a file access flaw that lets an attacker craft parameters on a data management protocol command to read files on the agent machine. CISA lists it as actively exploited, and the tags include ransomware use.","severity":"high","cvss":8.1,"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-servers","exploited","other","ransomware","veritas-backup-exec","windows"],"not_affected_if":["unknown"],"how_to_check":null,"fix":"Apply the vendor updates per Veritas instructions (CISA required action); exact fixed version unknown from sources.","status":"open","published_at":"2021-03-01T22:15:14+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:06:59+00:00","updated_at":"2026-10-23T22:29:04+00:00","category":"other","confidence":0.6,"triage":{"at":"2026-10-23T21:06:59Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor updates per Veritas instructions (CISA required action); exact fixed version unknown from sources.","reach":"network","impact":"high","summary":"Veritas Backup Exec Agent has a file access flaw that lets an attacker craft parameters on a data management protocol command to read files on the agent machine. CISA lists it as actively exploited, and the tags include ransomware use.","category":"other","who_cares":["veritas-backup-exec","backup-servers","windows"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker reads arbitrary files on the backup agent machine, possibly including credentials.","analyst_note":"Find affected and fixed Backup Exec Agent versions and the vendor advisory (Veritas security advisory for CVE-2021-27876) to fill how_to_check and fix.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["unknown"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000462,"input_tokens":2818,"output_tokens":361,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':12A,15A '-27876':13A,16A '21.2':10A,84C 'abl':118C 'access':42B,122C,154C 'activ':67B 'agent':20A,38B,61B,92C 'arbitrari':156C 'attack':47B,116C,152C 'authent':95C,113C,126C,139C 'backup':7A,18A,22A,25B,32B,36B,81C 'backup-serv':24B 'cisa':63B 'client':89C,130C 'command':55B,136C,150C 'communic':86C,104C 'complet':99C,124C 'connect':140C 'craft':48B,143C 'cve':11A,14A 'data':52B,133C 'discov':4A,78C 'due':106C 'exec':8A,19A,23A,33B,37B,82C 'execut':132C 'exploit':27B,68B 'file':41B,58B,157C 'flaw':43B 'gain':120C 'howev':105C 'includ':72B 'input':144C 'issu':2A,76C 'let':45B 'list':64B 'machin':62B 'manag':53B,134C 'one':147C 'paramet':49B,145C 'privileg':163C 'process':127C 'protocol':54B,135C 'ransomwar':29B,73B 'read':57B 'requir':93C 'scheme':114C 'secur':102C 'server':26B 'sha':112C 'subsequ':128C 'success':94C 'system':160C,162C 'tag':71B 'tls':103C 'typic':98C 'unauthor':121C 'use':74B,142C,161C 'verita':6A,31B,35B,80C 'veritas':17A,21A 'veritas-backup-exec':30B 'vulner':109C 'window':34B","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:N","cvss_by":"cve@mitre.org","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-27876","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27876","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":"2026-10-25T11:39:16+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-27876","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-27876","severity":null,"published_at":"2021-03-01T22:15:14+00:00","modified_at":"2026-06-17T03:45:32+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"}