CVE-2026-30040
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 · uneditedA heap overflow in the FSViewer.exe process of FastStone Image Viewer v8.3 allows attackers to cause a execute arbitrary code in the context of the current process via supplying a crafted JPEG 2000 (JP2) file.
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 heap overflow vulnerability in FastStone Image Viewer v8.3's FSViewer.exe process allows remote code execution via a specially crafted JPEG 2000 (.jp2) file. The vulnerability occurs during JP2 file parsing, where improper bounds checking leads to heap memory corruption, enabling attackers to execute arbitrary code in the context of the current process.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- None
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
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 FastStone Image Viewer installationSearch for FastStone Image Viewer in the Windows Start menu, check Program Files directory, or run 'Get-ItemProperty' in PowerShell for registry keys under HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall or HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\UninstallAffected if FastStone Image Viewer is found on the system
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Identify installed versionRight-click FSViewer.exe (typically in C:\Program Files\FastStone Image Viewer), select Properties, then Details tab to view the File Version. Alternatively, run PowerShell command: (Get-Item 'C:\Program Files\FastStone Image Viewer\FSViewer.exe').VersionInfo.FileVersionAffected if Version displays as 8.3 or falls within the v8.3 release line
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Verify vulnerable component existsConfirm FSViewer.exe is present in the FastStone Image Viewer installation directoryAffected if FSViewer.exe exists at the expected installation path
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Check JP2 file association or supportAttempt to open a benign .jp2 file with FastStone Image Viewer, or inspect File Type associations in the application's Settings > File Associations to confirm JP2 is associatedAffected if JP2 files can be opened or are associated with FSViewer.exe
A user is affected if FastStone Image Viewer version 8.3 is installed and the application can parse or display JPEG 2000 (.jp2) files.
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 vendor patches when available; until then, refrain from opening untrusted or externally-sourced JPEG 2000 files with FastStone Image Viewer.
- Consultation2.0 h
- Implementation8.0 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-2026-30040 — 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-2026-30040 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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