CVE-2021-27876

HIGH8.1

CISA KEV

Published 2021-03-01 · Updated 2026-06-17 · Source cve@mitre.org

Summary

CVE-2021-27876 is a high-severity (CVSS 8.1) vulnerability in Veritas Backup Exec Agent. CISA added it to the Known Exploited Vulnerabilities catalog on April 7, 2023, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by April 28, 2023. CISA also lists it as known to be used in ransomware campaigns, so it should be prioritised accordingly. Veritas has 3 vulnerabilities in the KEV catalog, 3 of them linked to ransomware.

All 3 known-exploited Veritas vulnerabilities →

Description

An issue was discovered in Veritas Backup Exec before 21.2. The communication between a client and an Agent requires successful authentication, which is typically completed over a secure TLS communication. However, due to a vulnerability in the SHA Authentication scheme, an attacker is able to gain unauthorized access and complete the authentication process. Subsequently, the client can execute data management protocol commands on the authenticated connection. By using crafted input parameters in one of these commands, an attacker can access an arbitrary file on the system using System privileges.

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

CISA Known-Exploited Vulnerability

Product: Veritas — Backup Exec Agent

Name: Veritas Backup Exec Agent File Access Vulnerability

Date added: 2023-04-07 · Due: 2023-04-28

USED IN RANSOMWARE

Required action: Apply updates per vendor instructions.

References

View on NVD

More exploited Veritas vulnerabilities

Most recently added to CISA KEV

CVE-2021-27877
RANSOMWARE
Backup Exec Agent — Veritas Backup Exec Agent Improper Authentication Vulnerability
added 2023-04-07
CVE-2021-27878
RANSOMWARE
Backup Exec Agent — Veritas Backup Exec Agent Command Execution Vulnerability
added 2023-04-07

View all →

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