CVE-2025-1240
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 · uneditedWinZip 7Z File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of WinZip. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of 7Z files. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-24986.
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 confidenceCVE-2025-1240 is an out-of-bounds write vulnerability in WinZip's 7Z file parsing functionality. The flaw results from insufficient validation of user-supplied data during 7Z archive processing, allowing a write operation to exceed allocated buffer boundaries. This memory corruption can be leveraged by an attacker to achieve remote code execution within the context of the WinZip process.
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>= 18.0, < 18.0.16371>= 27.0, < 27.0.16370>= 76.0, < 76.8CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/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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Verify WinZip is installedCheck for WinZip installation by looking in Program Files for WinZip folder, or check Windows Registry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall for WinZip entryAffected if WinZip is not found on the system, the CVE does not apply
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Determine installed WinZip versionRight-click the WinZip executable (winzip64.exe or winzip32.exe) in the installation folder, select Properties, and check the Details tab for the Product Version. Alternatively, run 'wzzip -?' from command line to display version information.Affected if Unable to determine version - further investigation needed
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Compare version against affected rangesMatch your installed version number against these vulnerable ranges: 18.0 through 18.0.16370, 27.0 through 27.0.16369, and 76.0 through 76.7. Versions outside these ranges or earlier than 18.0 are not affected.Affected if Installed version falls within 18.0 <= version < 18.0.16371, OR 27.0 <= version < 27.0.16370, OR 76.0 <= version < 76.8
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Confirm 7Z file handling capability is activeWinZip must have the 7Z parsing module enabled or have processed a 7Z file for this vulnerability to be exploitable. Check WinZip settings under Options > Configuration > Archive Formats to see if 7Z support is enabled.Affected if 7Z format support is enabled in WinZip and the application has been used to open 7Z archives
System is affected if WinZip is installed with 7Z support enabled and the installed version falls within any of the three vulnerable version ranges (18.0.x, 27.0.x, or 76.0.x through 76.7.x).
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 data18.0.1637127.0.1637076.8
Users should avoid opening 7Z files from untrusted sources until WinZip releases an official patch. Organizations may consider deploying additional file inspection at email gateways or endpoint controls to block suspicious 7Z attachments.
- Consultation4.0 h
- Implementation8.0 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-2025-1240 — 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-2025-1240 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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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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