CVE-2023-53959
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 · uneditedFileZilla Client 3.63.1 contains a DLL hijacking vulnerability that allows attackers to execute malicious code by placing a crafted TextShaping.dll in the application directory. Attackers can generate a reverse shell payload using msfvenom and replace the missing DLL to achieve remote code execution when the application launches.
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 confidenceFileZilla Client 3.63.1 is vulnerable to DLL hijacking via a crafted TextShaping.dll placed in the application directory. When the application launches, it loads the malicious DLL, enabling remote code execution with the privileges of the running user.
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= 3.63.1CVSS 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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Check FileZilla Client versionOpen FileZilla and go to Help > About FileZilla, or run 'filezilla --version' from command line, or check the version listed in Add/Remove Programs (Windows) or the installed package details (Linux)Affected if The installed version is exactly 3.63.1
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Locate the FileZilla application directoryOn Windows: typically C:\Program Files\FileZilla FTP Client\ or C:\Program Files (x86)\FileZilla FTP Client\. On Linux: typically /usr/bin/filezilla or /opt/filezilla. Check the installation path identified in the version check.Affected if The application directory path is identified and accessible for inspection
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Inspect for TextShaping.dll in application directoryNavigate to the FileZilla application directory and check if TextShaping.dll exists in that location. Use file explorer or run 'dir C:\Program Files\FileZilla FTP Client\TextShaping.dll' (Windows) or 'ls -la /usr/bin/filezilla/TextShaping.dll' (Linux)Affected if TextShaping.dll is present in the FileZilla application directory (this DLL is not normally required by FileZilla and its presence indicates potential hijacking)
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Verify application directory permissionsCheck if untrusted users have write access to the FileZilla application directory. On Windows, right-click the folder > Properties > Security and review write permissions. On Linux, run 'ls -ld /usr/bin/filezilla' and check group/world write bits.Affected if The application directory is writable by users who should not have write access (world-writable or writable by untrusted groups)
You are affected if FileZilla Client 3.63.1 is installed AND either TextShaping.dll exists in the application directory or the directory has weak permissions allowing untrusted users to write 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 dataUpdate FileZilla Client to the latest patched version. Additionally, ensure the application directory is protected from write access by untrusted users and verify no malicious DLLs are present.
- Consultation2.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-53959 — 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-2023-53959 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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