CVE-2021-21794
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 out-of-bounds write vulnerability exists in the TIF bits_per_sample processing functionality of Accusoft ImageGear 19.9. A specially crafted malformed file can lead to memory corruption. An attacker can provide a malicious file to trigger this vulnerability.
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 · moderate confidenceA high-severity out-of-bounds write vulnerability exists in Accusoft ImageGear 19.9's TIFF file parsing code, specifically in the bits_per_sample processing logic. When processing a specially crafted malformed TIFF file with malicious bits_per_sample values, the application writes data beyond allocated buffer boundaries, leading to heap memory corruption that can be exploited for arbitrary code execution.
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= 19.9CVSS 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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Confirm ImageGear installation and versionCheck the installed ImageGear version by inspecting the DLL file properties (e.g., ImageGear.dll) or querying the application's version info. On Windows, right-click the DLL and view Properties > Details, or use: Get-ItemProperty -Path 'C:\path\to\ImageGear.dll' | Select-Object VersionInfoAffected if The installed version is exactly 19.9 (exact match required per vendor scope)
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Identify TIFF processing functionalitySearch for ImageGear components that handle TIFF file formats. Look for TIFF-related DLLs or check application configuration for TIFF import/processing modules.Affected if The application uses ImageGear to process TIFF files and the TIFF module is loaded or enabled
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Check for untrusted TIFF input handlingReview application logs or code that handles TIFF file uploads/imports. Look for paths where users or external sources can submit TIFF files to ImageGear for processing.Affected if The application processes TIFF files from untrusted or external sources without prior validation
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Verify heap memory behavior (runtime check)If possible, run the application with memory debugging tools (like Application Verifier or address sanitizers) while processing a TIFF file with manipulated bits_per_sample values to observe heap corruption.Affected if Memory corruption or buffer overflow indicators appear during TIFF processing
A system is affected only if Accusoft ImageGear version 19.9 is installed AND the application uses ImageGear to process TIFF files from potentially untrusted sources.
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 dataApply the vendor patch for ImageGear 19.9 when available. Until then, implement file input validation and restrict ImageGear processing to sandboxed environments with limited privileges. Validate TIFF files through separate parsing before passing to ImageGear.
- Consultation4.0 h
- Implementation12.0 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-2021-21794 — 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-2021-21794 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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