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CVE-2021-27876

79
FAUCET Score

CVE-2021-27876 is a critical authentication bypass vulnerability affecting Veritas Backup Exec versions prior to 21.2. Attackers can exploit a flaw in the SHA Authentication scheme to gain unauthorized access to the agent, allowing them to execute data management commands with System privileges and access arbitrary files. This vulnerability carries a high CVSS score of 8.1, indicating a low-complexity network attack that can lead to high confidentiality and integrity impacts. Its FAUCET Risk Score of 99/100 further emphasizes its severe nature. The vulnerability is actively exploited, notably by the ALPHV (BlackCat) ransomware group, and is listed in CISA's KEV catalog. A Metasploit module exists for remote code execution, and it has garnered significant community discussion and media coverage due to its use in ransomware campaigns.

Impacted Technologies

VendorProductVersion(s)CPE
< 21.2CPE matchmatch criteria
cpe:2.3:a:veritas:backup_exec:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
13.41%
Probability of exploitation in next 30 days
EPSS Percentile
96.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
Added to KEV · Apr 7, 2023
Metasploit: Veritas Backup Exec Agent Remote Code Execution · Mar 1, 2021
This CVE's current EPSS score of 0.1341 is in the 95th percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
packetstormsecurity.com / files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html
ExploitThird Party AdvisoryVDB Entry
veritas.com / content/support/en_US/security/VTS21-001
Vendor Advisory