CVE-2026-32147: SFTP chroot bypass via path traversal in SSH_FXP_FSETSTAT

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-21 · updated 2026-10-26
Weakness: CWE-22

Description

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 before OTP 28.4.3, OTP 27.3.4.11 and OTP 26.2.5.20, corresponding to ssh from 3.0.1 before 5.5.3, 5.2.11.7 and 5.1.4.15.

Affected products

Erlang OTP: from 17.0 before 26.2.5.20; from 27.0 before 27.3.4.11; from 28.0 before 28.4.3 — fixed in 26.2.5.20, 27.3.4.11, 28.4.3
Erlang/Ssh: from 3.0.1 before 5.1.4.15; from 5.2 before 5.2.11.7; from 5.5 before 5.5.2 — fixed in 5.1.4.15, 5.2.11.7, 5.5.2

How to fix

Upgrade to a fixed version: Erlang OTP 26.2.5.20, 27.3.4.11, 28.4.3; Erlang/Ssh 5.1.4.15, 5.2.11.7, 5.5.2. Check the vendor advisory for mitigations.

References

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