CVE-2020-3979
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 · uneditedInstallBuilder for Qt Windows (versions prior to 20.7.0) installers look for plugins at a predictable location at initialization time, writable by non-admin users. While those plugins are not required, they are loaded if present, which could allow an attacker to plant a malicious library which could result in code execution with the security scope of the installer.
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 confidenceInstallBuilder for Qt Windows versions prior to 20.7.0 exhibit a DLL planting vulnerability where installers search for plugins at a predictable, user-writable path during initialization. A local attacker with non-admin privileges can place a malicious DLL in this location, which the installer will load upon execution, resulting in code execution with the installer's elevated privileges.
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< 20.7.0CVSS 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
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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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Check InstallBuilder versionLocate the InstallBuilder installation directory and check the version information (typically in installer executable properties, or run 'installer.exe /version' if supported)Affected if The installed version is any version prior to 20.7.0
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Identify the plugin search path used by InstallBuilderReview InstallBuilder documentation or runtime behavior to determine the default plugin search path; on Windows this is commonly within the user profile or application data areaAffected if The plugin search path resolves to a directory that is writable by non-privileged users
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Verify directory permissions on the plugin search pathUse icacls or file explorer to check if standard (non-admin) users have Write or Modify permissions on the identified plugin directoryAffected if Non-admin user accounts have write access to the directory where InstallBuilder searches for plugins
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Check for existing plugin DLL files in the search pathList all files in the plugin search path directory and inspect any DLL files present for legitimacyAffected if Unexpected or unknown DLL files exist in the plugin search directory
You are affected if InstallBuilder for Qt Windows is installed at a version below 20.7.0 AND the plugin search path is writable by non-admin users, allowing potential DLL planting.
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 data20.7.0
Upgrade InstallBuilder for Qt Windows to version 20.7.0 or later. If immediate patching is not feasible, verify that the plugin search path directory is not writable by non-admin users and remove any untrusted plugin files from that location.
- Consultation4.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3979 — 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-2020-3979 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
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