CVE-2021-27877
Veritas Backup Exec Agent Improper Authentication Vulnerability
- Published
- Mar 1, 2021
- Updated
- Oct 21, 2025
- Assigning CNA
- mitre
- Evidence observed
- Apr 7, 2023
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HHigh · next 30 days
- Percentile
- 99.2%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
CISA Known Exploited
This CVE appears in the CISA Known Exploited Vulnerabilities catalog.
Summary
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.
Sources
2- CVE-2021-27877-PoCExploit
A modified version of the Rapid7 Metasploit module for CVE-2021-27877 that supports direct command execution for reliable vulnerability validation. Includes documentation explaining the exploit workflow, the module modifications, and usage examples.
- CVE-2021-27876Exploit
Unauthenticated RCE exploit for Veritas Backup Exec Agent (CVE-2021-27876/77/78) — SHA auth bypass to SYSTEM via NDMP
Responsible use
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