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CVE-2021-27876

Published: Mar 1, 2021Updated: Nov 3, 2025 Sources: CVE List NVD BDUNVD-CWE-noinfo
8.1HIGH
NVD MITRE
EPSS Score
13.4%
Top 3.9%
CISA KEV
Active Exploitation
Since Apr 7, 2023
Exploits
1 Known
Remediation
Patch Available
Self-Check
OpenVAS

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.

In plain language

AI Act now

If you run Veritas Backup Exec versions older than 21.2, attackers over the network can bypass authentication and read any file on your server with system-level rights—this is a serious, actively abused risk for small businesses.

Executive summary

Unauthenticated network attackers can bypass the SHA Authentication scheme in Veritas Backup Exec and complete authentication, then use crafted data management protocol commands to read arbitrary files with SYSTEM-level privileges; this vulnerability is listed in the CISA KEV and has been used in ransomware campaigns.

If affected, business impact
Full system file disclosureRansomware enabling accessBackup data compromiseOperational disruption

What to do now

  1. Check your Veritas Backup Exec software version and confirm whether it is earlier than 21.2.
  2. Contact your IT/vendor team to confirm the exposed service is reachable from the network (and whether any Agent/client communication is permitted).
  3. Upgrade Veritas Backup Exec to a version that is fixed: 21.2 or later.
  4. If you cannot upgrade immediately, restrict network access to the Backup Exec/Agent services so they are not reachable from untrusted networks, then proceed with the upgrade as soon as possible.
Patch / advisory Usually a quick update

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

NVD-CWE-noinfo

Affected Products

Veritas Technologies LLC
commercial·USaka veritas, veritas tech
Backup ExecOn-prem
Enterprise Software / itsm-monitoring
veritas
commercial·US
backup execSaaSSaaS Service
Cloud & SaaS / saas-application
and 1 more affected products View all →

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Apr 7, 2023
Remediation due:Apr 28, 2023
Ransomware:Known ransomware use

Required action: Apply updates per vendor instructions.

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Is your org exposed to CVE-2021-27876?We can run the check for you — a free external exposure review, no install. Check my exposure

References

https://www.veritas.com/content/support/en_US/security/VTS21-001#issue2
veritas.com
http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html
packetstormsecurity.com
https://www.cisa.gov/sites/default/files/csv/known_exploited_vulnerabilities.csv
cisa.gov
and 1 more references View all →

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