CVE-2021-27877
Veritas Backup Exec Agent Improper Authentication Vulnerability
- High 8.2
- Exploited: added to CISA KEV 7 Apr 2023
- Used in ransomware campaigns
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.
Key facts
- Published
- 1 Mar 2021
- Last changed
- 21 Oct 2025
- Assigned by
- mitre
- KEV added
- 7 Apr 2023
- KEV fix due
- 28 Apr 2023
- Used in ransomware
- Yes, according to CISA
- EPSS
- 64.91% likely to be exploited in the next 30 days, higher than 99.261% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: yes; Technical impact: partial
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 8.2CVSS 3.1, Highfrom the CNA (mitre)
CVSS:3.1/AC:L/AV:N/A:N/C:H/I:L/PR:N/S:U/UI:N
What to do
- Apply updates per vendor instructions.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| n/a | n/a |
|
Timeline
- 1 Mar 2021 Published
- 7 Apr 2023 CVE-2021-27877 added to CISA KEV
- 7 Apr 2023 Added to the CISA KEV catalogue