IRONSMITHINTEL
HIGHCVSS8.2
|
Actively Exploited
|CISA KEV|CVE-2021-27877|Auth: none — unauthenticated|Reboot: required|Manual only

Veritas Backup Exec Agent Improper Authentication Vulnerability

Veritas Backup Exec (BE) Agent contains an improper authentication vulnerability that could allow an attacker unauthorized access to the BE Agent via SHA authentication scheme.

Published Mar 1, 2021 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, partial data tampering. CISA has confirmed use of this vulnerability in known ransomware campaigns — treat as high priority for remediation. Federal agencies are required to remediate by 2023-04-28 under CISA BOD 22-01.

How the attack worksNo clicks needed

This vulnerability 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. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

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Phishing link

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Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running backup exec: v < 21.2
Real-world incidentsWhat we've seen

Used in known ransomware campaigns. Threat-research write-up: http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply updates per vendor instructions.

References

    1
    Vendor advisory: https://www.veritas.com/support/en_US/security/VTS21-001
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2021-27877
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27877
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