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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 3 May 2022.
Windows Server 2008Operating system · Microsoft

CVE-2020-1350

CRITICAL · 10.0 CVSS v3.1 Published 2020-07-14
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

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
A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle requests, aka 'Windows DNS Server Remote Code Execution Vulnerability'.

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

CVE-2020-1350 (SIGRed) is a critical heap-based buffer overflow vulnerability in Windows DNS Server allowing unauthenticated remote attackers to execute arbitrary code via specially crafted DNS SIG records. The vulnerability affects Windows Server 2008 through 2019 and is network-exploitable without authentication.

MitigationApply Microsoft security update KB4565529 (July 2020) to all affected Windows DNS servers. As a temporary workaround, disable DNS recursion or restrict query sources until patching is complete.

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
Windows Server 2008Operating system
Affected:all versions= r2
Windows Server 2012Operating system
Affected:all versions= r2
Windows Server 2016Operating system
Affected:all versions
Windows Server 2019Operating system
Affected:all versions

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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. Verify DNS Server role is installed
    Use Server Manager to confirm the DNS Server role is installed, or run Get-WindowsFeature -Name DNS in PowerShell
    Affected if DNS Server role is installed on the machine
  2. Check Windows Server version
    Run 'winver' or use 'systeminfo' command to identify the Windows Server version and build number
    Affected if The installed version matches Windows Server 2008, 2008 R2, 2012, 2012 R2, 2016, or 2019 (all versions of these releases)
  3. Confirm DNS service is running
    Check if the DNS Server service (DNS) is started and listening on port 53 using 'Get-Service DNS' or 'netstat -ano | findstr :53'
    Affected if The DNS service is running and the server version falls within the affected product list

If the DNS Server role is active on any Windows Server 2008 through 2019, the system is potentially affected and should be evaluated against the Microsoft security update for CVE-2020-1350.

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
Patch available Apply the vendor patch
Vendor patch portal.msrc.microsoft.com →
Interim mitigation

Apply Microsoft security update KB4565529 (July 2020) to all affected Windows DNS servers. As a temporary workaround, disable DNS recursion or restrict query sources until patching is complete.

Recommended fix High confidence

Apply July 2020 Security Updates (KB4565539, KB4565541, KB4565547, KB4565549, KB4565551, KB4565553) for respective Windows Server versions

  1. Identify the specific Windows Server version and build running DNS server role using 'winver' or 'systeminfo'
  2. Apply the July 2020 Cumulative Security Update for Windows Server from Microsoft Update Catalog or WSUS
  3. For Windows Server 2016: Install KB4565549 or later monthly rollup
  4. For Windows Server 2019: Install KB4565547 or later monthly rollup
  5. For Windows Server 2012 R2: Install KB4565553 or later
  6. For Windows Server 2012: Install KB4565551 or later
  7. For Windows Server 2008 R2: Install KB4565539 (Monthly Rollup) or KB4565541 (Security Only)
  8. For Windows Server 2008: Install KB4565539 (Monthly Rollup) or KB4565541 (Security Only)
Caveat Windows Server 2008 and 2008 R2 reached end of support; consider migrating to newer OS if on extended support is required

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

Fix this in Windows Server 2008 Exploited in the wild — priority engagement
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

Scan for this in your stack

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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-2020-1350 in production — separate from our analysis above.

No notes yet

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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