Is CVE-2021-27877 in the CISA KEV catalog?

Yes. CVE-2021-27877 is on the CISA Known Exploited Vulnerabilities list, added 2023-04-07, and has known ransomware campaign use.

What is the CVSS severity of CVE-2021-27877?

CVE-2021-27877 has a CVSS v3 base score of 8.2 (HIGH).

What is the EPSS score for CVE-2021-27877?

CVE-2021-27877 has an EPSS score of 64.91% (99th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-27877

HIGHCISA KEVEPSS 99th pctl

8.2

CVSS v3

NVD

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 v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

64.91%probability of exploitation in 30 days

99thpercentile

Very high risk: more likely to be exploited than 99% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Veritas Backup Exec Agent Improper Authentication Vulnerability

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.

Apply updates per vendor instructions.

Remediation due: 2023-04-28

Associated with ransomware campaigns

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-03.