CVE-2021-27877: Veritas Backup Exec Agent Improper Authentication Vulnerability
Vulnerability summary
CVE-2021-27877 is a critical (CVSS 9.8) vulnerability in Veritas Backup Exec Agent. It is known to be exploited: CISA lists it, first on 07-04-2023. It has been used in ransomware campaigns. EPSS estimates a 64.91% chance of exploitation in the next 30 days, higher than 99.2% of scored vulnerabilities. 2 public exploits are recorded.
Timeline
- 01-03-2021PublishedVulnerability first disclosed.
- 07-04-2023Added to CISA KEVVeritas Backup Exec Agent Improper Authentication Vulnerability
- 28-04-2023CISA remediation dueApply updates per vendor instructions.
- 21-10-2025Last modifiedVulnerability information updated.
Description
An issue was discovered in Veritas Backup Exec before 21.2. It supports multiple authentication schemes: SHA authentication is one of these. This authentication scheme is no longer used in current versions of the product, but hadn't yet been disabled. An attacker could remotely exploit this scheme to gain unauthorized access to an Agent and execute privileged commands.
CVSS metrics
3 scores · 2 sources · 2 versions- CVE.orgCNA8.2HighCVSS:3.1/AC:L/AV:N/A:N/C:H/I:L/PR:N/S:U/UI:NDiffers
EPSS trend
Probability
64.91%
Chance of exploitation in the next 30 days
Percentile
99%
Versus all other CVEs
30-day change
0.00 pp
From 64.91% on 18-09-2026
Known exploited
Compare KEV catalogs
CISA KEVListed- Added
- 07-04-2023
- Federal due date
- 28-04-2023
CISA required action
Apply updates per vendor instructions. www.veritas.com/support/en_US/security/VTS21-001 nvd.nist.gov/vuln/detail/CVE-2021-27877
Public exploits
2 foundExploit Reference (packetstormsecurity.com)
Maturity: unknown
Veritas Backup Exec Agent Remote Code Execution
exploit/multi/veritas/beagent_sha_auth_rce
Maturity: weaponized
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Veritas1 product
- backup_exec< 21.2
1 vendor · 1 product
References
3 links- packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.htmlX Refsource MISCExploitThird Party AdvisoryVDB Entry
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27877Government ResourceUS Government Resource