How severe is CVE-2021-27877?

CVE-2021-27877 has a CVSS 3.1 base score of 8.2 (HIGH). EPSS estimates a 64.9% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2021-27877: Veritas Backup Exec Agent Improper Authentication

CISA Known Exploited Vulnerabilities

Veritas Backup Exec Agent Improper Authentication Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2023-04-07

Remediation due

2023-04-28

Ransomware

Known use

Required action
Apply updates per vendor instructions.

CISA notes
https://www.veritas.com/support/en_US/security/VTS21-001; https://nvd.nist.gov/vuln/detail/CVE-2021-27877

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.

Severity

CVSS 3.1 · CNA8.2 HIGH

CVSS:3.1/AC:L/AV:N/A:N/C:H/I:L/PR:N/S:U/UI:N

SSVC · CISA-ADP

Exploitationactive

Automatableyes

Technical impactpartial

Exploitation Context

as of October 17, 2026

All KEV statistics→

CISA added CVE-2021-27877 to the KEV catalog 767 days after its CVE record was published. The median for entries added in 2023 is 12 days.
It is one of 3 Veritas entries in the CISA KEV catalog, and one of 3 added in 2023.
Its current EPSS score (64.9%) is higher than that of 56% of CISA KEV entries.

Affected Products

Vendor	Product	Affected versions
-	-	n/a

References

2 Links

Other references

Record Details

Published

2021-03-01

Last updated

2025-10-21

Assigner (CNA)

mitre

Credited to

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.