CVE intelligence and bounded remediation

CVE-2021-41636 — Melag Ftp Server security vulnerability

Medium CVSS 6.8

MELAG FTP Server 2.2.0.4 allows an attacker to use the CWD command to break out of the FTP servers root directory and operate on the entire operating system, while the access restrictions of the user running the FTP server apply.

Severity
Medium
CVSS
6.8 (2.0)
Published
2022-06-24
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-22

Affected products

  • melag / ftp_server / 2.2.0.4

Matched remediation archetype

Path traversal, unsafe upload, and file handling

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Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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