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EEF-CVE-2026-23942
No affected components available
Summary
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal.
This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2.
The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root.
This issue affects OTP from OTP 17.0 before OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.
Workaround
* Use OS-level chroot to run the Erlang VM/SFTP server process in an isolated filesystem environment. * Ensure that no sensitive or precious data is readable or writable by the OS user running the Erlang VM. * Ensure that the SFTP server port is not reachable from untrusted machines. * Use directory naming conventions that avoid common prefixes (e.g., /home/users/alice/ instead of /home/user1/).
Configuration
The SFTP subsystem must be enabled on the SSH server, the SSH port must be reachable by the attacker, and a root directory must be configured. This is the case when ssh_sftpd is included in the subsystems option with a root parameter and there exist sibling directories sharing the same name prefix as the root.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability.
Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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