CVE-2021-27876

An issue was discovered in Veritas Backup Exec before 21.2. The communication between a client and an Agent requires successful authentication…

Browse: All 2021 CVEs · All vendors

CVSS score
8.1 High
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CISA KEV
Yes — actively exploited (added 2023-04-07, remediation due 2023-04-28)
Ransomware
Known ransomware campaign use
Weakness (CWE)
CWE-287
Published
2021-03-01
Last modified
2026-06-17
NVD status
Analyzed

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.

Affected products

Affected ranges per NVD CPE data; confirm exact versions in the vendor advisory.

Required action (CISA)

Apply updates per vendor instructions. Federal remediation deadline: 2023-04-28.

How to prioritize this

This vulnerability is on the CISA KEV list, meaning it is being actively exploited — treat it as urgent regardless of the raw CVSS number. Use the live CVE lookup for the latest NVD data, and the CVSS 3.1 calculator to model your own environmental score. For the actively exploited vulnerabilities that matter this week, read The Exploit HQ daily security brief.

References

FAQ

Is CVE-2021-27876 actively exploited?

Yes. CISA added CVE-2021-27876 to its Known Exploited Vulnerabilities (KEV) catalog on 2023-04-07, with a federal remediation deadline of 2023-04-28. A KEV listing means real-world exploitation is confirmed, so patching this should be prioritized above many higher-CVSS bugs that aren't being exploited.

What is the CVSS score of CVE-2021-27876?

CVE-2021-27876 has a CVSS base score of 8.1 (High). Its vector string is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

Related vulnerabilities

Data source: NVD & CISA KEV. Shown as-is; nothing added. Last generated from NVD data — re-check the live tool for updates.