CVE-2026-69649: Windows Raw Image Extension Thumbnail Preview Remote Code Execution

HERMES

HERMES THREAT SCORE & ZERO-CLICK PREVIEW ATTACK SURFACE

Target: Windows Raw Image Extension (RawImageExtension.dll / RawImageWicCodec.dll)

Confidence: 96%

93 / 100

CRITICAL

Measures real-world operational relevance, exploit weaponization, and active threat posture.

Dimension Breakdown

Exploitability 19 / 20

Threat Activity 17 / 20

Weaponization 18 / 20

Exposure 19 / 20

Prevalence 20 / 20

Impact 19 / 20

Exploit Maturity 18 / 20

Attack Chain Potential 20 / 20

⚖️ Divergence & Operational Rationale

CVSS v3.1 rates CVE-2026-69649 at 8.8 (HIGH, CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). The Hermes Threat Score elevates operational risk to 93 (CRITICAL) because exploitation is triggered automatically when Windows Explorer generates directory thumbnails or preview icons without requiring the victim to open the file.

🕸️ Connected Knowledge Graph & Provenance

CVE-2026-69649: Windows Raw Image Extension Thumbnail Preview Remote Code ExecutionVULNERABILITY

Connected Nodes: 1

Active Relationships (Outgoing)

→ affectsPRODUCTMicrosoft Windows & Windows Server

98% VERY_HIGH

Software platform affected by security vulnerabilities and agentic attack patterns.

🔍 Why is this related? (Evidence & Provenance)

“Confirmed security vulnerability in Microsoft Windows & Windows Server documented in Hermes dossier.”

Supporting Verified Evidence:

• [vulnerability_report]
• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

Critical File Parser Alert: Zero-Click Folder Browsing RCE

CVSS v3.1 : 8.8 HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) / CWE-122: Heap-based Buffer Overflow. Addressed in Microsoft’s September 2026 security release affecting the Windows Raw Image Extension codec package distributed via Microsoft Store and Windows enterprise image deployments.

Executive Summary

CVE-2026-69649 is a remote code execution vulnerability in the Windows Raw Image Extension (RawImageExtension.dll). The flaw stems from insufficient boundary validation when decoding embedded camera maker notes and SubIFD metadata in digital camera RAW image formats (.CR2, .NEF, .ARW, .DNG). When a user browses a folder containing a weaponized RAW file (locally or over SMB/WebDAV shares), the Windows shell thumbnail generator automatically processes the image, triggering a heap overflow that grants arbitrary code execution in the context of explorer.exe.

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1. Technical Context & Affected Software Matrix

The Windows Raw Image Extension enables native support for viewing and thumbnailing camera-specific RAW images in Windows Explorer, Windows Photos, and other Windows Imaging Component (WIC) consumers.

Parameter	Technical Specification	Threat Intelligence Context
CVE Identifier	CVE-2026-69649	MSRC Bulletin September 2026
Vulnerable Component	Windows Raw Image Extension (RawImageExtension.dll / RawImageWicCodec.dll)	WIC Codec Library for Camera RAW formats
CWE Weakness	CWE-122: Heap-based Buffer Overflow	Unbounded decompression in SubIFD strip decoding
CVSS v3.1 Score	8.8 (HIGH / Hermes Severity 93 CRITICAL)	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Delivery Vectors	SMB/WebDAV shares, downloaded archives, email attachments, USB media	Zero-click on directory navigation in Windows Explorer
Affected Platforms	Windows 10, Windows 11 (22H2-24H2), Windows Server 2022/2025	Systems with Microsoft.RawImageExtension package
Remediation Method	Microsoft Store automatic update / Package 2.4.21001.0	Automatic store distribution or manual enterprise provisioning

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2. In-Depth Technical Decomposition & Root Cause

The Windows Raw Image Extension relies on a customized LibRaw/WIC parser to decode diverse camera sensor formats based on the TIFF/EP and DNG standards. Images contain multiple Image File Directories (IFDs), including SubIFDs pointing to compressed preview tiles and thumbnails.

When parsing SubIFD tags (Tag 0x014A), the codec decodes image strips defined by StripOffsets (Tag 0x0111) and StripByteCounts (Tag 0x0117). In RawImageWicCodec.dll, the decompression routine allocates a heap buffer based on calculated image dimensions Width * Height * BitsPerSample / 8.

However, when processing an image where the StripByteCounts specifies an uncompressed payload exceeding the dimensions declared in the parent SubIFD, the parser fails to clamp the decoded stream length:

// Conceptual depiction of CVE-2026-69649 heap buffer overflow
HRESULT RawImageDecoder::DecodeSubIFDStrip(
    PRAW_IFD_ENTRY pIfdEntry,
    PBYTE pbRawStream,
    DWORD cbStreamSize
) {
    // Allocation size calculated from declared dimensions
    DWORD cbExpectedSize = pIfdEntry->ImageWidth * pIfdEntry->ImageHeight * (pIfdEntry->BitsPerSample / 8);

    // Allocate heap chunk based on expected dimensions
    PBYTE pbDestBuffer = (PBYTE)HeapAlloc(GetProcessHeap(), 0, cbExpectedSize);
    if (!pbDestBuffer) return E_OUTOFMEMORY;

    // VULNERABILITY: If StripByteCounts declares a larger buffer
    // or compression decompression expands beyond cbExpectedSize:
    DWORD cbDecompressedBytes = 0;
    HRESULT hr = DecompressBayerTile(
        pbRawStream + pIfdEntry->StripOffset,
        pIfdEntry->StripByteCount, // Untrusted size from file header
        pbDestBuffer,              // Destination chunk
        &cbDecompressedBytes       // Fails to enforce cbExpectedSize limit!
    );

    // Unbounded write corrupts adjacent heap chunks in explorer.exe
    return hr;
}

Because Windows Explorer invokes thumbnail handlers out-of-process or in background worker threads upon opening any directory, an attacker achieves execution without the user explicitly clicking or opening the file.

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3. Attack Vectors & Enterprise Threat Scenarios

[ Attacker hosts crafted .CR2/.DNG on SMB/WebDAV share or ZIP ]
               │
               ▼ (Victim navigates to folder in Windows Explorer)
[ Windows Shell invokes Thumbnail Provider (thumbcache) ]
               │
               ▼ (RawImageWicCodec.dll parses SubIFD metadata)
[ Trigger CVE-2026-69649 Heap Buffer Overflow in explorer.exe ]
               │
               ▼ (Arbitrary Code Execution under logged-on user)
[ Extract Cached Credentials / Inject C2 Beacon ]
               │
               ▼ (Local Privilege Escalation to SYSTEM)
[ Lateral Movement across Active Directory ]

Forensic Correlation with Hermes Codex

• Access Tokens and Security Context: Understanding how malicious shellcode in explorer.exe inherits the user’s primary access token and restricted group memberships. See AD-06: Windows access tokens and security context.
• Privilege Escalation Paths: Attackers use the initial user-mode foothold to chain local privilege elevation flaws to attain Domain Admin. See AD-04: Local Admin vs Domain Admin.
• Lateral Movement Across Active Directory: Utilizing harvested Kerberos TGTs to pivot across member servers. See AD-24: Lateral movement across Active Directory domains.

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4. Forensic Detection, Artefacts & Event IDs

DFIR analysts investigating potential exploitation of CVE-2026-69649 should focus on Windows Explorer crash telemetry and shell thumbnail cache records:

Key Event IDs & System Artefacts

• Windows Thumbnail Cache Database: %LocalAppData%\Microsoft\Windows\Explorer\thumbcache_*.db. Forensic tools (e.g. Thumbcache Viewer) can extract cached image fragments of the exploit payload.
• Application Error Event ID 1000: Crash of explorer.exe or RuntimeBroker.exe with faulting module RawImageExtension.dll or RawImageWicCodec.dll and exception code 0xc0000005 (Access Violation) or 0xc0000374 (STATUS_HEAP_CORRUPTION).
• Windows Shell Bags: HKCU\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\Bags confirming the folder containing the malicious file was rendered in Explorer.
• Zone.Identifier ADS: Check if downloaded image files contain Alternate Data Stream Zone.Identifier indicating external web provenance (ZoneId=3).

KQL Query: Suspicious Process Spawning from Windows Explorer

DeviceProcessEvents
| where InitiatingProcessFileName =~ "explorer.exe"
| where FileName in~ ("cmd.exe", "powershell.exe", "powershell_ise.exe", "cscript.exe", "wscript.exe", "mshta.exe", "rundll32.exe")
| project Timestamp, DeviceName, InitiatingProcessFileName, FileName, ProcessCommandLine, AccountName
| order by Timestamp desc

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5. Remediation, Hardening & Defensive Engineering

1. Update Raw Image Extension Package: Ensure Microsoft Store package is updated to version 2.4.21001.0 or higher using PowerShell:

   Get-AppxPackage -Name Microsoft.RawImageExtension* | Select-Object Name, Version

2. Disable Thumbnails in Windows Explorer via GPO: Configure Turn off the display of thumbnails and only display icons under: User Configuration \ Administrative Templates \ Windows Components \ File Explorer.
3. Block Untrusted Outbound SMB/WebDAV: Block outbound TCP port 445 and TCP port 80/443 WebDAV connections to external untrusted IP ranges at perimeter firewalls.