Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2021-27878

Backup Exec

Veritas / Backup Exec

Watch CVE-2021-27878 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
24.0%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-27878 is a vulnerability affecting Veritas Backup Exec. An issue was discovered in Veritas Backup Exec before 21.2. The communication between a client and an Agent requires successful authentication, which is...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV.

Who is affected?

Veritas / Backup Exec.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

An issue was discovered in Veritas Backup Exec before 21.2

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. The attacker could use one of these commands to execute an arbitrary command on the system using system privileges.

Published
01 Mar 2021
Exploitation Reported
07 Apr 2023
Attack vector
Remote
Complexity
Low
Privileges
Low
User interaction
None

Tags

ransomware metasploit cisa malware

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 07 Apr 2023

A trusted third party reported exploitation.

Used in malware

CISA

Recorded 07 Apr 2023

Malware families have been linked to exploitation of this CVE.

Proof of concept available

Recorded 28 Apr 2025

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2023-04-07 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/multi/veritas/beagent_sha_auth_rce.rb 28 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

24.0%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

All CVSS Scores

CVSS v3.1 8.8 High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 9.0 High

AV:N/AC:L/Au:S/C:C/I:C/A:C

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

beagent_sha_auth_rce

metasploit · Created Unknown

Metasploit module for CVE-2021-27878

Timeline

From disclosure to observed exploitation

  1. 15:02 UTC

    Metasploit module available

    Exploit module available

  2. 15:02 UTC

    Public PoC available

    Public proof-of-concept code published

  3. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  4. 00:00 UTC

    First public exploitation report

    Exploit observed in malware

  5. 21:49 UTC

    CVE published

    Vulnerability disclosed publicly

  6. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-27878

Sample API response 
{
  "cve_id": "CVE-2021-27878",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.23952,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}