CVE-2026-48855: SFTP READLINK Leaks Absolute Backend Filesystem Path When Root Is Configured

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-10 · updated 2026-10-25
Weakness: CWE-200

Description

Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Erlang OTP ssh (ssh_sftpd module) allows File Discovery. The SSH_FXP_READLINK handler in ssh_sftpd sends the raw result of file:read_link/2 to the client without calling chroot_filename/2 to strip the backend root prefix. An authenticated SFTP client can create a symlink inside the chroot pointing to /; ssh_sftpd resolves the target to the absolute backend root and stores it on disk. Reading the symlink back via SSH_FXP_READLINK returns that absolute path, for example /data/sftp, instead of the chrooted value /. The information disclosed is the absolute filesystem path of the SFTP root directory and of any symlink targets within it. No file contents, credentials, or access to paths outside the root directory are obtainable through this issue alone. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 27.3.4.13, OTP 28.5.0.2, and OTP 29.0.2, corresponding to ssh from 3.0.1 before 5.2.11.8, 5.5.2.1, and 6.0.1. Whether OTP before OTP 17.0, corresponding to ssh before 3.0.1, is affected is unknown.

Affected products

Erlang OTP: from 17.0 before 27.3.4.13; from 28.0 before 28.5.0.2; from 29.0 before 29.0.2 — fixed in 27.3.4.13, 28.5.0.2, 29.0.2
Erlang/Ssh: from 3.0.1 before 5.2.11.8; from 5.5 before 5.5.2.1; from 6.0 before 6.0.1 — fixed in 5.2.11.8, 5.5.2.1, 6.0.1

How to fix

Upgrade to a fixed version: Erlang OTP 27.3.4.13, 28.5.0.2, 29.0.2; Erlang/Ssh 5.2.11.8, 5.5.2.1, 6.0.1. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-48855 or the next vulnerability affects your stack