CVE-2021-27877
Veritas Backup Exec Agent Improper Authentication Vulnerability
Veritas Backup Exec Agent
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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 7 April 2023. US federal agencies were required to remediate it by 28 April 2023. CISA records this vulnerability as known to be used in ransomware campaigns.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 64.9%, which is higher than 99.3% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Frequently asked questions
Is CVE-2021-27877 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2021-27877.
What does CVE-2021-27877 affect?
CVE-2021-27877 affects Veritas Backup Exec Agent. 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.
How severe is CVE-2021-27877?
CVE-2021-27877 is rated HIGH with a CVSS base score of 8.2. EPSS puts the probability of exploitation in the next 30 days at 64.9%, higher than 99.3% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 28 April 2023.
How should organisations respond to CVE-2021-27877?
Apply the vendor patch for Veritas Backup Exec Agent as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.