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CVE-2021-40444

Path Traversal: Is CVE-2021-40444 real, exploitable, or a false positive? Here's the community verdict.

signals

public sources

Exploited in wild
Yes
CISA KEV
Public exploit
Metasploit +1
Metasploit/EDB/PoC
Base severity
8.8 High
CVSS
Exploitation prob.
97%
FIRST EPSS
Weakness
CWE-22 · Path Traversal
CWE

Confirmed exploited in the wild. Patch this first, regardless of the base score.

public exploits

links to sources — we don’t host code

A working exploit is publicly available from a maintained source. Treat this as higher urgency and verify your exposure.

baseline read

auto · not a community verdict

Real — exploited in the wild

CISA confirms active exploitation. Treat scanner hits as true positives unless your specific version or config is unaffected.

Based on CISA KEV

Confirm or dispute →
Affected:Microsoft

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

<p>Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents.</p> <p>An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.</p> <p>Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: “Suspicious Cpl File Execution”.</p> <p>Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.</p> <p>Please see the <strong>Mitigations</strong> and <strong>Workaround</strong> sections for important information about steps you can take to protect your system from this vulnerability.</p> <p><strong>UPDATE</strong> September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. Please see the FAQ for important information about which updates are applicable to your system.</p>

Published

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In your experience, is this finding real and exploitable?

awaiting field verdicts
Real, but not a risk here
Not a real issue

Curated baseline: TruePositive's read from public sources is Real & exploitable — a starting point, not a community verdict.

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Field notes & remediation

Verdicts are the quick signal. Notes are the evidence and fixes behind them.

  • 0
    Field note · TruePositive EditorialCurated

    Microsoft MSHTML Remote Code Execution Vulnerability — Microsoft MSHTML contains a unspecified vulnerability that allows for remote code execution. Listed in the CISA KEV catalog (added 2021-11-03) — confirmed exploited in the wild, not theoretical. It is linked to known ransomware campaigns. FIRST EPSS puts the chance of exploitation in the next 30 days at ~97%. Treat it as real and prioritize remediation over triage.

  • 0
    Remediation · TruePositive EditorialCurated

    Required action for Microsoft MSHTML: Apply updates per vendor instructions. CISA set a federal remediation due date of 2021-11-17. After patching, verify the vulnerable path is no longer reachable before closing the finding.

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Same weakness: CWE-22 · Path Traversal.