# CVE-2021-27876: Veritas Backup Exec Agent File Access Vulnerability

> CVE-2021-27876: Veritas Backup Exec Agent File Access Vulnerability. CVSS 8.1 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-27876
Last updated: 2025-10-21T23:25:53Z

- Published: 2021-03-01 21:49 UTC · Updated: 2025-10-21 23:25 UTC · Assigner: mitre
- CVSS: 8.1 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AC:L/AV:N/A:N/C:H/I:H/PR:L/S:U/UI:N
- EPSS: 13.5%, 96th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2023-04-07, federal due date 2023-04-28, ransomware use: Known

## 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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- Veritas: Backup Exec Agent

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-27876)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-27876)
- [http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html](http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html)
- [https://www.veritas.com/content/support/en\_US/security/VTS21-001\#issue2](https://www.veritas.com/content/support/en_US/security/VTS21-001#issue2)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-27876 · Markdown: https://rewindex.com/cve/CVE-2021-27876.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-27876 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:29.062Z