CVE-2021-27877: in the CISA KEV catalogue
Veritas Backup Exec Agent Improper Authentication Vulnerability. CISA added CVE-2021-27877 to the Known Exploited Vulnerabilities catalogue on 2023-04-07 with a default due date of 2023-04-28. Known ransomware campaign use: Known. Forensic triage flag: No.
Veritas Backup Exec (BE) Agent contains an improper authentication vulnerability that could allow an attacker unauthorized access to the BE Agent via SHA authentication scheme. (CISA description)
- Vendor / product
- Veritas Backup Exec Agent
- CWE
- CWE-287
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 65%, percentile 99 (scored 2026-11-03)
EPSS puts about 65 in 100 odds (65%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2021-27877 in the CISA KEV catalogue?
Yes. CISA added CVE-2021-27877 (Veritas Backup Exec Agent Improper Authentication Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-04-07. CISA's default due date for it is 2023-04-28.
Is CVE-2021-27877 used in ransomware attacks?
CISA marks known ransomware campaign use as Known for CVE-2021-27877.
What should I do about CVE-2021-27877?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2021-27877