CVE-2023-53959: FileZilla Client · Uncontrolled Search Path Element
Affects FileZilla ClientSource CVE Database V5
Not known to be exploited · CVSS 8.5 High.
Data as of 26 Oct 2026, 08:30 UTC
- EPSS
- 0.8% chance of exploitation in 30 days – higher than 58% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 19 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| filezilla-project FileZilla Client | Affected
| Fixed in– |
AI-suggested
To mitigate this vulnerability, organizations should: 1) Immediately restrict write permissions on directories where FileZilla Client is installed to prevent unauthorized DLL placement. 2) Monitor application directories for unexpected or suspicious DLL files, especially TextShaping.dll. 3) Educate users about the risks of running outdated software and the importance of not executing unknown files. 4) Apply vendor patches or updates as soon as they are released to address this vulnerability. 5) Employ endpoint detection and response (EDR) solutions to detect anomalous behaviors indicative of DLL hijacking or reverse shell activity. 6) Use application whitelisting to prevent unauthorized DLLs from loading. 7) Limit local user privileges to reduce the risk of attackers placing malicious files in application directories. 8) Consider alternative secure file transfer clients with better security postures if immediate patching is not feasible. These steps go beyond generic advice by focusing on controlling the application environment and monitoring for specific indicators related to this vulnerability.
Description
FileZilla 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.