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CVE-2021-28476

Public exploit available. Not confirmed exploited in the wild yet. Fixed versions are out.

CVSS 3.19.9CriticalEPSS percentile99th39% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
Public exploit: 1 sourceFix5 products8 fixed builds listed below

Published Updated Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Microsoft Windows 10 Version 1803Affected: ≥ 10.0.0, < 10.0.17134.2207Upgrade to: 10.0.17134.2207Affected: ≥ 10.0.0, < 10.0.17763.1935Upgrade to: 10.0.17763.1935Affected: ≥ 10.0.0, < 10.0.18363.1556Upgrade to: 10.0.18363.1556Affected: ≥ 10.0.0, < 10.0.19041.982Upgrade to: 10.0.19041.982 + 2 more branchesStated by: CVE record
  • Microsoft Windows Server 2019Affected: ≥ 10.0.0, < 10.0.17763.1935Upgrade to: 10.0.17763.1935Stated by: CVE record
  • Microsoft Windows Server, version 1909Affected: ≥ 10.0.0, < 10.0.18363.1556Upgrade to: 10.0.18363.1556Affected: ≥ 10.0.0, < 10.0.19041.982Upgrade to: 10.0.19041.982Affected: ≥ 10.0.0, < 10.0.19042.982Upgrade to: 10.0.19042.982Stated by: CVE record
  • Microsoft Windows Server 2016Affected: ≥ 10.0.0, < 10.0.14393.4401Upgrade to: 10.0.14393.4401Stated by: CVE record
  • Microsoft Windows 7 Service Pack 1Affected: ≥ 6.1.0, < 6.1.7601.24597Upgrade to: 6.1.7601.24597Affected: ≥ 6.1.0, < 6.1.7601.24598Upgrade to: 6.1.7601.24598Stated by: CVE record

Versions as the sources state them. 5 more products have version data. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Windows Hyper-V Remote Code Execution Vulnerability

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS99th
Public exploit
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

1 source with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

39% chance of exploitation activity in the next 30 days, which ranks it in the 99th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 471 days before any public exploit.

  1. OpenVAS check added
  2. EPSS band changehigh → moderate
  3. EPSS band changemoderate → high
  4. EPSS band changehigh → moderate
  5. Public exploit / PoCsource: packetstorm
  6. Patch availablerecord updated

Affected products

And 46 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 9.9 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

Sources

References in the record

And 2 more references. See all after sign-in

Analysis on the cve.tools blog

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We'll flag the next CVE, public exploit or patch for Windows 10 Version 1803, not every advisory. This one: public exploit.