CVE-2016-5725: Improper Limitation of a Pathname to a Restricted Directory in JCraft JSch

com.jcraft:jsch Updated 02 Oct 2025

Summary

13/05/2022

Disclosed on

CVE-2016-5725

CVE

Yes i

Fix available

Moderate

Severity

5.9

CVSS Score

CVE-2016-5725: Improper Limitation of a Pathname to a Restricted Directory in JCraft JSch. Affects com.jcraft:jsch versions < 0.1.54. Fixed in 0.1.54. How to fix ↓

Also tracked for

jsch · Debian:11

The same CVE-2016-5725 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.

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Background

JCraft JSch is a Java implementation of the SSH2 protocol. It provides a simple interface for connecting to SSH servers and performing secure file transfers. JSch is widely used in various applications and libraries for SSH communication. However, versions before 0.1.54 on Windows are vulnerable to a directory traversal attack when the mode is set to ChannelSftp.OVERWRITE. This vulnerability allows remote SFTP servers to write to arbitrary files by exploiting a '..' (dot dot backslash) sequence in the response to a recursive GET command.

Vulnerability Detail

The vulnerability arises from a lack of proper limitation on the pathname during file transfers. By including the '..' sequence in the response, an attacker can navigate to parent directories and overwrite files outside the intended directory. This can lead to unauthorized modification or disclosure of sensitive information. The severity of this vulnerability is rated as MODERATE with a CVSS score of 5.9.

How To Fix

Minimum fixed version

0.1.54

This is the first release that contains the fix.

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Workaround

If updating the library is not immediately feasible, a temporary workaround can be implemented by disabling the ChannelSftp.OVERWRITE mode. By avoiding the use of this mode, the vulnerability can be mitigated. However, this workaround may impact the functionality of certain file transfer operations, so it is advised to update to the latest version of the library as soon as possible.

Conclusion

In conclusion, the JCraft JSch library versions before 0.1.54 on Windows are vulnerable to a directory traversal attack. This can be mitigated by updating the library to the latest version or temporarily disabling the ChannelSftp.OVERWRITE mode. For further support on vulnerability remediation, please contact DevNack.com.

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