CVE-2021-27877

Name: CVE-2021-27877
Creator: NVD / NIST
Published: 2021-03-01T22:15:14.46+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10Actively ExploitedEPSS 64.91%

Last modified Jun 17, 2026

CVE-2021-27877 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. An issue was discovered in Veritas Backup Exec before 21.2. It supports multiple authentication schemes: SHA authentication is one of these. CISA has confirmed active exploitation in the wild. EPSS estimates a 64.91% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

64.91%

99.1th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Apr 28, 2023.

Affected Software

Vendor	Product	Versions
Veritas	Backup Exec	< 21.2

References

http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://www.veritas.com/content/support/en_US/security/VTS21-001#issue1Vendor Advisory
http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://www.veritas.com/content/support/en_US/security/VTS21-001#issue1Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27877US Government Resource

Timeline

Published: Mar 1, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-27877?

How severe is CVE-2021-27877?

CVE-2021-27877 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 64.91% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2021-27877?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-27877?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST