Which products and versions are affected by CVE-2021-27877?

Affected: Backup Exec (Veritas). The full list is in the CVE brief.

Is CVE-2021-27877 being exploited in the wild?

It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 3, 2023 and is known to be used in ransomware campaigns.

Is CVE-2021-27877 in the CISA KEV catalog?

Yes. It was added on Apr 7, 2023 with a federal remediation due date of Apr 28, 2023.

Is there a public exploit for CVE-2021-27877?

Public exploit code is available.

Is there a fix for CVE-2021-27877?

Fixed versions are available, including Backup Exec 21.2.

How urgently should CVE-2021-27877 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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Vulnerability Intelligence

CVE-2021-27877

CriticalExploitedPublic exploit

It supports multiple authentication schemes: SHA authentication is one of these.

Published Mar 1, 2021 · Updated Nov 3, 2025

Key Facts

Patch immediately

CVE-2021-27877 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Backup Exec (Veritas).
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 3, 2023 and is known to be used in ransomware campaigns. Public exploit code is available.
EPSS estimates a 65% probability of exploitation in the next 30 days.
Fixed versions are available, including Backup Exec 21.2.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v3.1

9.8

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

EPSS (30-day exploit likelihood)

65%

Higher than 99.2% of all scored CVEs

Exploited in the wild

Yes

4 catalog listings, used by ransomware

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2021-27877 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

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.

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
CISA KEV	Apr 7, 2023	Apr 28, 2023	Known
Industry KEV feed	Apr 3, 2023	Apr 28, 2023	Known
CIRCL KEV	Apr 7, 2023	Apr 28, 2023	Known
ENISA EUVD	Apr 7, 2023	n/a	Not reported

Required action: Apply updates per vendor instructions.

Affected Products

1 affected entries in total

Product	Affected versions	Fixed in
Backup ExecVeritas	See advisory	21.2

Patched Releases

Backup Exec

21.2

Timeline

Publicly disclosed
Mar 1, 2021
Added to Industry KEV feed
Apr 3, 2023
Added to CISA KEV
Apr 7, 2023
Added to CIRCL KEV
Apr 7, 2023
Added to ENISA EUVD
Apr 7, 2023
Last updated
Nov 3, 2025

References

8 more references in the full CVE brief

FAQ

Common Questions.

An issue was discovered in Veritas Backup Exec before 21.2.
Affected: Backup Exec (Veritas). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 3, 2023 and is known to be used in ransomware campaigns.
Yes. It was added on Apr 7, 2023 with a federal remediation due date of Apr 28, 2023.
Public exploit code is available.
Fixed versions are available, including Backup Exec 21.2.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Is CVE-2021-27877 Running On Your Attack Surface?

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