CVE-2021-26608
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 · uneditedAn arbitrary file download and execution vulnerability was found in the HShell.dll of handysoft Co., Ltd groupware ActiveX module. This issue is due to missing support for integrity check of download URL or downloaded file hash.
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 confidenceA critical arbitrary file download and execution vulnerability exists in the HShell.dll ActiveX component of handysoft Co., Ltd groupware. The component lacks integrity verification mechanisms, allowing attackers to download and execute arbitrary files by manipulating the download URL or by serving malicious files without hash validation.
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= 1.7.4.5= 2.0.3.5= 4.0.1.6CVSS 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
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 checksWork through these to decide whether this CVE applies to you.
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Locate Handysoft Hshell installationSearch for the CLM or Handysoft groupware application in Program Files, or check registry keys under HKLM\SOFTWARE\Handysoft or HKLM\SOFTWARE\WOW6432Node\Handysoft for the installation directory.Affected if Handysoft CLM or Hshell groupware software is installed on the system
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Identify HShell.dll versionNavigate to the Hshell installation folder and locate HShell.dll. Right-click the file, select Properties, and view the Version tab to obtain the exact file version.Affected if The HShell.dll version matches 1.7.4.5, 2.0.3.5, or 4.0.1.6 (exact versions)
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Verify ActiveX component registrationOpen Windows Registry and check for HShell.dll registration under HKLM\SOFTWARE\Classes\CLSID or search for CLSIDs containing 'HShell' to confirm the ActiveX control is registered.Affected if The HShell ActiveX control is registered in the Windows registry
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Confirm browser ActiveX settingsIn Internet Explorer, access Tools > Internet Options > Security > Custom Level and verify if ActiveX controls and plug-ins are set to Enabled or Prompt for the relevant zones. Alternatively, check Group Policy settings under Computer Configuration > Administrative Templates > Windows Components > Internet Explorer > Security Features.Affected if ActiveX controls are permitted to run in browser security zones that have internet access
A system is affected if Handysoft Hshell CLM is installed with HShell.dll at version 1.7.4.5, 2.0.3.5, or 4.0.1.6 AND the ActiveX component is registered and allowed to execute in browsers.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataImplement URL allowlist validation and cryptographic hash verification for downloaded files before execution. Until a vendor patch is available, restrict ActiveX controls in browsers and limit network access to trusted sources only.
- Consultation4.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26608 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-26608 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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