CVE-2021-35971
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 · uneditedVeeam Backup and Replication 10 before 10.0.1.4854 P20210609 and 11 before 11.0.0.837 P20210507 mishandles deserialization during Microsoft .NET remoting.
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 confidenceVeeam Backup and Replication versions 10 and 11 contain a deserialization vulnerability in the Microsoft .NET remoting component. This improper handling of deserialization can allow remote attackers to execute arbitrary code by sending specially crafted serialized .NET objects, potentially achieving unauthenticated remote code execution with SYSTEM privileges.
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>= 10.0, < 10.0.1.4854>= 11.0, < 11.0.0.837CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Check installed Veeam Backup and Replication versionOpen the Veeam Backup and Replication client and navigate to Help > About, or locate the version in Windows Programs and FeaturesAffected if Version is 10.0.0.0 through 10.0.1.4853, or 11.0.0.0 through 11.0.0.836
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Verify .NET remoting is in useExamine Veeam service configurations and listening ports - .NET remoting typically uses TCP ports 6180-6182 or similar ranges for inter-process communication in Veeam infrastructureAffected if The .NET remoting service is active and bound to network-accessible interfaces
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Review network exposure of Veeam serverCheck firewall rules and binding addresses on the Veeam server to determine if remoting ports are reachable from untrusted networksAffected if Veeam remoting ports are exposed to external networks or untrusted VLANs without network segmentation
The environment is affected if the installed version falls within the vulnerable ranges and .NET remoting is enabled and reachable from a network attacker.
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.
dbcve · scoped10.0.1.485411.0.0.837
Apply the vendor-supplied patches: update to Veeam Backup and Replication 10.0.1.4854 (P20210609) or 11.0.0.837 (P20210507) or later. Prior to patching, restrict network access to the backup infrastructure and disable .NET remoting if not required.
Veeam Backup & Replication 10.0.1.4854 (P20210609) or later for version 10; Veeam Backup & Replication 11.0.0.837 (P20210507) or later for version 11
- Verify current Veeam Backup & Replication version by opening the Veeam Backup & Replication console and checking About, or running Get-VBRServerInfo in PowerShell
- Download the appropriate update from Veeam's support portal: https://www.veeam.com/kb
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation2.0 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 $3,552.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35971 — 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-2021-35971 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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- 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
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