dbcve.org
Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 28 Apr 2023. Known ransomware use
Backup ExecApplication · Veritas

CVE-2021-27877

CRITICAL · 9.8 CVSS v3.1 Published 2021-03-01
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Veritas Backup Exec before version 21.2 contains a legacy SHA authentication scheme that was not disabled despite being deprecated in current product versions. This allows remote unauthenticated attackers to bypass authentication and execute privileged commands on connected Backup Exec Agents.

MitigationUpgrade Veritas Backup Exec to version 21.2 or later, which disables the legacy SHA authentication scheme.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Backup ExecApplication
Affected:< 21.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check the installed Backup Exec version
    Retrieve the installed version of Veritas Backup Exec from the system (via Add/Remove Programs, registry, or Backup Exec console) and compare it to version 21.2
    Affected if The installed version is earlier than 21.2
  2. Identify if the legacy SHA authentication scheme is enabled
    Examine the Backup Exec authentication or security configuration settings to determine whether the deprecated SHA-based authentication mechanism is still active
    Affected if The deprecated SHA authentication scheme remains enabled in the configuration
  3. Verify agent listener port exposure
    Check the network configuration for Backup Exec Agent listener ports (typically TCP 6100-6106 and related RPC ports) to determine if they are accessible from untrusted networks
    Affected if Agent communication ports are open to untrusted or external network segments
  4. Confirm remote agent connectivity is permitted
    Review Backup Exec server settings to determine whether remote agent installations or remote command execution is permitted without additional restrictions
    Affected if Remote agents can connect to the server without strong authentication or network-level restrictions

If the installed Backup Exec version is earlier than 21.2 and the deprecated SHA authentication scheme is enabled or exposed, the environment is vulnerable to CVE-2021-27877.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 21.2 or later
Fixed in 21.2
Interim mitigation

Upgrade Veritas Backup Exec to version 21.2 or later, which disables the legacy SHA authentication scheme.

Recommended fix High confidence

Backup Exec 21.2

  1. Back up your current Backup Exec configuration and database before upgrading
  2. Download Backup Exec version 21.2 or later from the official Veritas downloads portal (www.veritas.com)
  3. Review the Backup Exec upgrade documentation and release notes for version 21.2
  4. Run the Backup Exec 21.2 installer on the server
  5. Follow the on-screen prompts to complete the upgrade process
  6. After upgrading, verify that the SHA authentication scheme has been disabled in the product settings
  7. Test that Backup Exec agents are functioning correctly post-upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Backup Exec Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-27877 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-27877 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data