Vsphere ReplicationApplication · VMware
CVE-2021-21976
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 · uneditedvSphere Replication 8.3.x prior to 8.3.1.2, 8.2.x prior to 8.2.1.1, 8.1.x prior to 8.1.2.3 and 6.5.x prior to 6.5.1.5 contain a post-authentication command injection vulnerability which may allow an authenticated admin user to perform a remote code execution.
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 confidencevSphere Replication versions 8.3.x, 8.2.x, 8.1.x, and 6.5.x contain a post-authentication command injection vulnerability. An authenticated administrator can execute arbitrary commands on the underlying operating system, leading to full RCE.
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
Vsphere ReplicationApplication
>= 6.5.0, < 6.5.1.5>= 8.1.0, < 8.1.2.3>= 8.2.0, < 8.2.1.1>= 8.3.0, < 8.3.1.2CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify if vSphere Replication is installedLocate the vSphere Replication appliance in your vCenter inventory or check for the VR service on the affected system. In the vSphere Client, navigate to Sites > Recovery > vSphere Replication to confirm the product is deployed.Affected if vSphere Replication appliance or service is present in the environment
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Determine the installed vSphere Replication versionAccess the vSphere Replication admin UI, typically at https://<vr-appliance-ip>:5480, and check the version displayed on the summary page. Alternatively, log into the VR appliance via SSH and run the command 'vadumper --version' or check /opt/vmware/vcops/vr/config/vr.properties for the version string.Affected if the installed version falls within any of these ranges: 6.5.0 to 6.5.1.4, 8.1.0 to 8.1.2.2, 8.2.0 to 8.2.1.0, or 8.3.0 to 8.3.1.1
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Verify admin authentication is enabled or accessibleConfirm that the vSphere Replication administrative interface is accessible and that admin accounts exist. Check if the /login endpoint responds and if administrative users have been configured in the VR admin portal.Affected if administrator authentication is enabled and the admin interface is reachable (the vulnerability is post-authentication, so valid admin credentials are required for exploitation)
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Inspect for unusual post-authentication activityReview vSphere Replication logs in /var/log/vmware/vr/ and vCenter events for any unexpected commands, script executions, or admin actions occurring after login. Look for entries containing shell invocations, file writes, or network connections initiated by the VR service account.Affected if evidence exists of unauthorized command execution, unexpected scripts, or anomalous admin activity in logs after authentication
You are affected if vSphere Replication is installed and the version falls within 6.5.0 to 6.5.1.4, 8.1.0 to 8.1.2.2, 8.2.0 to 8.2.1.0, or 8.3.0 to 8.3.1.1, and an attacker with valid admin credentials could potentially execute commands.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor data6.5.1.58.1.2.38.2.1.1
Upgrade vSphere Replication to version 8.3.1.2, 8.2.1.1, 8.1.2.3, or 6.5.1.5 or later to patch the command injection flaw. Restrict admin access and monitor for unusual post-authentication activity as an interim control.
Fix this in Vsphere Replication
Scoped from the published advisory
- Consultation4.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,448.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-21976 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-21976 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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