Vulnerability · Published Jul 2, 2026 · Assigned by EEF
CVE-2026-53422SFTP REALPATH path-existence oracle allowing filesystem enumeration outside configured root
Low 2.3
In plain English
A low-severity security flaw in OTP from Erlang. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Observable 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. The 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. An 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. The 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. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routine ssh_sftpd:handle_op/4. This issue affects OTP from OTP 17.0 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssh from 3.0.1 before 6.0.2, 5.5.2.2 and 5.2.11.9.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | erlang | no fix listed | DEBIAN-CVE-2026-53422 |
| Debian:13 | erlang | 1:27.3.4.1+dfsg-1+deb13u3 | DEBIAN-CVE-2026-53422 |
| Debian:14 | erlang | 1:29.0.3+dfsg-1 | DEBIAN-CVE-2026-53422 |
| Ubuntu:22.04:LTS | erlang | 1:24.2.1+dfsg-1ubuntu0.8 | UBUNTU-CVE-2026-53422 |
| Ubuntu:22.04:LTS | erlang | 1:24.2.1+dfsg-1ubuntu0.8 | USN-8901-1 |
| Ubuntu:24.04:LTS | erlang | 1:25.3.2.8+dfsg-1ubuntu4.8 | USN-8901-1 |
| Ubuntu:24.04:LTS | erlang | 1:25.3.2.8+dfsg-1ubuntu4.8 | UBUNTU-CVE-2026-53422 |
| Ubuntu:25.10 | erlang | no fix listed | UBUNTU-CVE-2026-53422 |
| Ubuntu:26.04:LTS | erlang | 1:27.3.4.6+dfsg-1ubuntu0.2 | USN-8901-1 |
| Ubuntu:26.04:LTS | erlang | 1:27.3.4.6+dfsg-1ubuntu0.2 | UBUNTU-CVE-2026-53422 |
Affected products (as reported)
Weakness: CWE-204 · Vector: 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
References
- https://github.com/erlang/otp/security/advisories/GHSA-h9pw-h5w4-h976 vendor-advisory, related
- https://cna.erlef.org/cves/CVE-2026-53422.html related
- https://osv.dev/vulnerability/EEF-CVE-2026-53422 related
- https://www.erlang.org/doc/system/versions.html#order-of-versions x_version-scheme
- https://github.com/erlang/otp/commit/059e5785ef8c1d423820ca633fb7b37f47645172 patch
- https://github.com/erlang/otp/commit/86622cfaacf57a02c7645d1999f946846b504c94 patch
- https://github.com/erlang/otp/commit/c5a8f50ae68888ff243c5c741a06d2b3a4b48b7a patch