Security Resilience

CVE-2023-53959

Filezilla-Project Filezilla Client 3.63.1

Public PoC
Published
19 December 2025
Modified
09 April 2026
Patch / advisory
View advisory
CVSS Score v4 8.5
Click a component to see what it means
Raw vectorCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0085 57th percentile
Risk Priority 35 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-53959 is a high-severity Uncontrolled Search Path Element (CWE-427) vulnerability in Filezilla-Project Filezilla Client. Its CVSS base score is 8.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception by Search Order Hijacking (T1574.008); ranked in the top 43% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to CM-6 (Configuration Settings) and AC-3 (Access Enforcement) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-53959 is a DLL hijacking vulnerability (CWE-427) in FileZilla Client version 3.63.1. The flaw occurs because the application attempts to load a missing TextShaping.dll from its directory, enabling attackers to place a malicious version of this DLL in the application directory to execute arbitrary code upon launch.

The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating it is exploitable remotely with low complexity, no privileges, and no user interaction. Attackers can generate a reverse shell payload using msfvenom, replace the missing DLL with it, and achieve remote code execution when a user launches the affected FileZilla Client.

Advisories and references, including those from Vulncheck (vulncheck.com/advisories/filezilla-client-dll-hijacking-via-missing-textshapingdll) and a proof-of-concept exploit on Exploit-DB (exploit-db.com/exploits/51267), detail the issue, while the FileZilla project site (filezilla-project.org) provides relevant updates for practitioners to review.

OWASP Top 10 for Web (2025)

A08:2025 Software or Data Integrity Failures

EU & UK References

Vulnerability Data

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…

more

remote code execution when the application launches.

CWE(s)
CWE-427

Related Threats

MITRE ATT&CK Enterprise Techniques

T1574.008 Path Interception by Search Order Hijacking Stealth
Adversaries may execute their own malicious payloads by hijacking the search order used to load other programs.
attack.mitre.org →
T1574.004 Dylib Hijacking Stealth
Adversaries may execute their own payloads by placing a malicious dynamic library (dylib) with an expected name in a path a victim application searches at runtime.
attack.mitre.org →
T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-31497Same product: Filezilla-Project Filezilla Client
CVE-2025-26404Shared CWE-427
CVE-2025-22838Shared CWE-427
CVE-2024-36253Shared CWE-427
CVE-2025-40979Shared CWE-427
CVE-2025-60749Shared CWE-427
CVE-2023-27513Shared CWE-427
CVE-2024-23940Shared CWE-427
CVE-2026-41567Shared CWE-427
CVE-2025-9164Shared CWE-427

Affected Assets

filezilla-project
filezilla client
3.63.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 2 hardening rules · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

CM-6 Configuration Settings good match

Establishes restrictive configuration settings that can define and lock down approved search paths.

AC-3 Access Enforcement partial match

Enforces approved authorizations so that only intended actors can place or modify elements in the search path.

AC-6 Least Privilege partial match

Limits privileges so unintended actors cannot write to or control directories in the product's search path.

CM-5 Access Restrictions for Change partial match

Restricts logical and physical access to change system configuration, including search-path settings and directories.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-01 partial match
blocks

Hardened configuration baselines can enforce safe search-path settings and reduce exposure.

PR.PS-05 partial match
blocks

Execution allow-listing can block malicious binaries placed in hijackable search locations.

PR.PS-06 partial match
blocks

Secure-development practices directly address design of search paths and resource loading.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248577 OL 8 must enable kernel parameters to enforce Discretionary Access Control (DAC) on symlinks. blocks CWE-427

References