{"affected":[{"ranges":[{"events":[{"introduced":"84adefa331c4159d432d22840663c38f155cd4c1"},{"fixed":"059e5785ef8c1d423820ca633fb7b37f47645172"},{"fixed":"86622cfaacf57a02c7645d1999f946846b504c94"},{"fixed":"c5a8f50ae68888ff243c5c741a06d2b3a4b48b7a"}],"repo":"https://github.com/erlang/otp","type":"GIT"}]}],"aliases":["GHSA-h9pw-h5w4-h976","CVE-2026-53422"],"credits":[{"name":"Mohamed Ali IBNAL HAJALI / Ericsson","type":"FINDER"},{"name":"Michał Wąsowski","type":"REMEDIATION_DEVELOPER"},{"name":"Jakub Witczak","type":"REMEDIATION_REVIEWER"}],"database_specific":{"capec_ids":["CAPEC-54"],"cpe_ids":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-204"]},"details":"## Summary\n\nObservable Response Discrepancy vulnerability in Erlang OTP ssh (ssh\\_sftpd module) allows an authenticated SFTP user to enumerate the existence of files and directories outside the configured root directory.\n\nThe SSH\\_FXP\\_REALPATH handler in ssh\\_sftpd calls relate\\_file\\_name/3 with Canonicalize=false, unlike every other SFTP operation handler. This allows .. components in the requested path to bypass the is\\_within\\_root/2 check without being resolved. The un-canonicalized path then enters resolve\\_symlinks/2, which walks up the directory tree above the configured root and issues read\\_link() syscalls on arbitrary filesystem paths.\n\nAn authenticated SFTP client can exploit this by sending a REALPATH request with a crafted traversal path. The server response differs depending on whether the target path exists on the host filesystem (SSH\\_FXP\\_NAME when the path resolves successfully, SSH\\_FX\\_NO\\_SUCH\\_FILE when it does not). This creates a path-existence oracle that an attacker can use to enumerate the filesystem structure outside the configured root, including the existence of sensitive files, directories, and mount points.\n\nThe vulnerability leaks only the existence of paths. No file contents, credentials, or write access are obtainable through this issue alone. The information gained may assist further attacks when combined with other vulnerabilities.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh\\_sftpd.erl and program routine ssh\\_sftpd:handle\\_op/4.\n\nThis issue affects OTP from OTP 17.0 until OTP 29.0.3, 28.5.0.3, and 27.3.4.14 corresponding to ssh from 3.0.1 until 6.0.2, 5.5.2.2, and 5.2.11.9.\n\n## Workaround\n\n\\* Use OS-level chroot to run the Erlang VM or SFTP server process in an isolated filesystem environment, eliminating reliance on the application-level root option.\n\\* Ensure the SFTP server port on the machine running the Erlang/OTP SFTP server is not reachable from untrusted machines.\n\\* Ensure that no sensitive information (usernames, project names, mount topology) is inferrable from the existence or non-existence of paths on the host filesystem.\n\n## Configuration\n\nThe SFTP subsystem must be configured with the root option in ssh\\_sftpd:subsystem\\_spec/1, and the operator must rely on it to provide filesystem path isolation. The root option is not set by default.","id":"EEF-CVE-2026-53422","modified":"2026-07-02T16:06:03.802Z","published":"2026-07-02T16:06:03.802Z","references":[{"type":"ADVISORY","url":"https://github.com/erlang/otp/security/advisories/GHSA-h9pw-h5w4-h976"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-53422.html"},{"type":"WEB","url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/059e5785ef8c1d423820ca633fb7b37f47645172"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/86622cfaacf57a02c7645d1999f946846b504c94"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/c5a8f50ae68888ff243c5c741a06d2b3a4b48b7a"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"SFTP REALPATH path-existence oracle allowing filesystem enumeration outside configured root","upstream":[]}