CVE-2026-32147

Summary

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated SFTP user to modify file attributes outside the configured chroot directory.

The SFTP daemon (ssh_sftpd) stores the raw, user-supplied path in file handles instead of the chroot-resolved path. When SSH_FXP_FSETSTAT is issued on such a handle, file attributes (permissions, ownership, timestamps) are modified on the real filesystem path, bypassing the root directory boundary entirely.

Any authenticated SFTP user on a server configured with the root option can modify file attributes of files outside the intended chroot boundary. The prerequisite is that a target file must exist on the real filesystem at the same relative path. Note that this vulnerability only allows modification of file attributes; file contents cannot be read or altered through this attack vector.

If the SSH daemon runs as root, this enables direct privilege escalation: an attacker can set the setuid bit on any binary, change ownership of sensitive files, or make system configuration world-writable.

This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:do_open/4 and ssh_sftpd:handle_op/4.

This issue affects OTP from OTP 17.0 until OTP 28.4.3, 27.3.4.11, and 26.2.5.20 corresponding to ssh from 3.01 until 5.5.3, 5.2.11.7, and 5.1.4.15.

Affected Software

VendorProductVersion RangeStatus
ErlangOTP3.01 < *affected
ErlangOTP17.0 < *affected
ErlangOTP07b8f441ca711f9812fad9e9115bab3c3aa92f79 < *affected

Weaknesses

  • CWE-22: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Workarounds

  • Do not use the root option in ssh_sftpd:subsystem_spec/1, and instead rely on OS-level chroot or container isolation to confine SFTP users.
  • Ensure the Erlang VM is not running as a privileged OS user. Running the VM as an unprivileged user limits the impact of this vulnerability, since attribute modifications are constrained by that user's OS-level permissions.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References