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ExploitedIn CISA KEVFix available

CVE-2021-27876

Exploitation confirmed. First attested on 2023-04-07 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2021-03-01
  • Fixed in21.2

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-03-0122:15CVE publishedNVD
  2. 2023-04-07Added to the CISA KEV catalogCISA KEV
  3. 2023-04-07Listed as exploited by GCVEGCVE
  4. 2023-04-07Exploitation first reportedCISA KEV
  5. 2023-12-2205:01SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-27876?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-27876?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Veritas backup exec
BranchAffectedFixed in
21.2< 21.221.2

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Veritas backup exec to 21.2
  2. CISA’s required action: Apply updates per vendor instructions.due 2023-04-28

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedwingerbijay/CVE-2021-27876hyderpwn/veritas-backup
PoC-in-GitHub
Metasploit modules
1 moduleexploit/multi/veritas/beagent_sha_auth_rcerank: excellentModule metadata: Metasploit Framework, © Rapid7, Inc., BSD-3-Clause.
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2023-04-07
Patch Due Date
2023-04-28
Ransomware Use
Known
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Published
2021-03-01
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-9j5v-h34p-h6g6

Frequently asked questions

What is CVE-2021-27876?

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.

Is CVE-2021-27876 actively exploited?

Yes. CVE-2021-27876 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2023-04-28.

What is the CVSS score for CVE-2021-27876?

CVE-2021-27876 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

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Sources for this record