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Mallory
HighCISA KEVExploited in the wildPublic exploit

Microsoft Word OLE Security Feature Bypass

IdentifiersCVE-2026-21514CWE-807· Reliance on Untrusted Inputs in a…

CVE-2026-21514 is a Microsoft Office Word security feature bypass vulnerability caused by reliance on untrusted inputs in a security decision. Available reporting indicates that a specially crafted malicious Word/Office document can bypass OLE mitigations in Microsoft 365 and Microsoft Office that are intended to protect users from dangerous COM/OLE controls and embedded objects. Multiple sources describe the issue as suppressing or bypassing the usual security warnings when a victim opens the document, thereby exposing COM/OLE functionality that can then be abused in follow-on exploitation. The vulnerability is triggered when a user opens the malicious Office file; Microsoft noted that the Preview Pane is not an attack vector. Reporting also notes observed in-the-wild exploitation and references use of LNK files in related attack chains.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an unauthorized attacker to bypass Word/Office security protections around OLE/COM content and embedded objects. By removing or suppressing those protections and warnings, the flaw can enable follow-on malicious activity, including abuse of dangerous COM/OLE controls and potential remote code execution in the context of the user who opened the document. The vulnerability has been reported as actively exploited in the wild and included in CISA's KEV catalog.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by preventing users from opening untrusted Office documents, especially files received via email, downloads, or links. Enforce attachment and document-origin controls, block or restrict Office documents from untrusted sources, and monitor for suspicious Word documents attempting to invoke COM/OLE behavior or embedded object handling. Because exploitation requires opening the document and the Preview Pane is not an attack vector, focus mitigations on document delivery, user execution paths, and detection of abnormal Office child-process or COM/OLE activity. Information about any vendor-provided workaround beyond patching is not available in the provided content.

Remediation

Patch, then assume compromise.

Apply Microsoft's February 2026 security updates for all affected Microsoft Office and Microsoft 365 products. Content provided indicates affected product lines include Microsoft 365 Apps for Enterprise, Microsoft Office LTSC 2024, Microsoft Office LTSC 2021, and Microsoft Office LTSC for Mac 2024/2021; use the relevant Microsoft release notes or update packages for each platform and channel. Prioritize remediation because the vulnerability is publicly known and actively exploited.
PUBLIC EXPLOITS

Exploits

1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.

VALID 1 / 1 TOTALView more in app
CVE-2026-21514_CVE-2026-21510MaturityPoCVerified exploit

This repository is a small exploit-builder project with 4 files: a license, a README, and two Python scripts. It is not a scanner or detector; it generates malicious artifacts for a document-based exploit chain targeting CVE-2026-21514 and CVE-2026-21510. Structure and purpose: - README.md documents the intended exploit chain and experimentation notes. It describes a Protected View/SBX bypass component and an RCE component, including CLSID changes, XML/object changes, and possible DLL-to-CPL substitution. - gen_rtf.py builds exploit.rtf by inserting a UTF-16-style null-padded UNC/WebDAV path into a large hardcoded RTF/OLE blob. The embedded path is \\127.0.0.1@80/final.lnk, indicating the document is meant to cause retrieval of a remote LNK over port 80 via WebDAV-like UNC syntax. - make_lnk.py builds final.lnk from hardcoded hex templates plus a null-padded remote payload path. The referenced payload path is \\127.0.0.1\cc.dll. The script comments explicitly suggest generating the DLL with msfvenom using windows/meterpreter/reverse_tcp. Main exploit capabilities: - Generates a malicious RTF lure document. - Embeds a remote UNC/WebDAV path to a malicious LNK file. - Generates a malicious LNK that references a remote DLL payload over SMB/UNC. - Includes embedded HTML/JavaScript/ActiveX logic inside the LNK data, apparently to trigger file/URL handling and object loading behavior. - Supports straightforward operator customization by changing the hardcoded remote paths and replacing the DLL payload. Operationally, this is an exploit builder rather than a full delivery framework. The payload is basic and hardcoded, so OPERATIONAL is the best fit rather than WEAPONIZED. The code is clearly intended to achieve code execution on a vulnerable Windows/Office target by chaining remote file retrieval and DLL loading.

ChaitanyaHaritashDisclosed May 4, 2026pythonmarkdownfilenetworkweb
EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft Corporation365 Appsapplication
Microsoft CorporationOffice 2021application
Microsoft CorporationOffice 2024application
Microsoft CorporationOffice Long Term Servicing Channelapplication
Microsoft CorporationOffice Macos 2021application
Microsoft CorporationOffice Macos 2024application
Microsoft CorporationWordapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

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Threat actor evidence

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Associated malware

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Detection signatures2

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Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity39

Community discussion across Reddit, Mastodon, and other social sources.