Summary
File System Bounds Escape
Background
When windows separators exist within the path (\), path.resolve leaves the upper pointers intact and allows the user to move beyond the root folder defined for that user. We did not take that into account when creating the path resolve function.
Workarounds
There are no workarounds for windows servers. Hosting the server on a different OS mitigates the issue.
References
Issues:
https://github.com/autovance/ftp-srv/issues/167
https://github.com/autovance/ftp-srv/issues/225
For more information
If you have any questions or comments about this advisory:
Open an issue at https://github.com/autovance/ftp-srv.
Please email us directly; [email protected].
Impact
Clients of FTP servers utilizing ftp-srv hosted on Windows machines can escape the FTP user's defined root folder using the expected FTP commands, for example, CWD and UPDR.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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None at the moment.
Frequently Asked Questions
- What is CVE-2020-26299? CVE-2020-26299 is a medium-severity path traversal vulnerability in ftp-srv (npm), affecting versions < 4.4.0. It is fixed in 4.4.0. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- Which versions of ftp-srv are affected by CVE-2020-26299? ftp-srv (npm) versions < 4.4.0 is affected.
- Is there a fix for CVE-2020-26299? Yes. CVE-2020-26299 is fixed in 4.4.0. Upgrade to this version or later.
- Is CVE-2020-26299 exploitable, and should I be worried? Whether CVE-2020-26299 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-26299 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-26299? Upgrade
ftp-srvto 4.4.0 or later.