CVE-2026-53422 (GCVE-0-2026-53422)

Vulnerability from cvelistv5 – Published: 2026-07-02 16:06 – Updated: 2026-07-03 04:28
VLAI
Title
SFTP REALPATH path-existence oracle allowing filesystem enumeration outside configured root
Summary
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 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.
Severity
2.3 (Low)
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
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-204 - Observable Response Discrepancy
Assigner
EEF
References
Impacted products
Vendor Product Version
Erlang OTP Affected: 3.0.1 , < * (otp)
    cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
 Create a notification for this product.
Erlang OTP Affected: 17.0 , < * (otp)
Affected: 84adefa331c4159d432d22840663c38f155cd4c1 , < * (git)
    cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
 Create a notification for this product.
Credits
Mohamed Ali IBNAL HAJALI / Ericsson Michał Wąsowski Jakub Witczak
Show details on NVD website
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    "vulnrichment": {
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existence or non-existence of paths on the host filesystem.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cul\u003e\u003cli\u003eUse OS-level chroot to run the Erlang VM or SFTP server process in an isolated filesystem environment, eliminating reliance on the application-level \u003ctt\u003eroot\u003c/tt\u003e option.\u003c/li\u003e\u003cli\u003eEnsure the SFTP server port on the machine running the Erlang/OTP SFTP server is not reachable from untrusted machines.\u003c/li\u003e\u003cli\u003eEnsure that no sensitive information (usernames, project names, mount topology) is inferrable from the existence or non-existence of paths on the host filesystem.\u003c/li\u003e\u003c/ul\u003e\", \"base64\": false}]}], \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"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.\\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.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eObservable Response Discrepancy vulnerability in Erlang OTP \u003ctt\u003essh\u003c/tt\u003e (\u003ctt\u003essh_sftpd\u003c/tt\u003e module) allows an authenticated SFTP user to enumerate the existence of files and directories outside the configured root directory.\u003c/p\u003e\u003cp\u003eThe \u003ctt\u003eSSH_FXP_REALPATH\u003c/tt\u003e handler in \u003ctt\u003essh_sftpd\u003c/tt\u003e calls \u003ctt\u003erelate_file_name/3\u003c/tt\u003e with \u003ctt\u003eCanonicalize=false\u003c/tt\u003e, unlike every other SFTP operation handler. 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The information gained may assist further attacks when combined with other vulnerabilities.\u003c/p\u003e\u003cp\u003eThis vulnerability is associated with program files \u003ctt\u003elib/ssh/src/ssh_sftpd.erl\u003c/tt\u003e and program routine \u003ctt\u003essh_sftpd:handle_op/4\u003c/tt\u003e.\u003c/p\u003e\u003cp\u003eThis issue affects OTP from OTP 17.0 until OTP 29.0.3, 28.5.0.3, and 27.3.4.14 corresponding to \u003ctt\u003essh\u003c/tt\u003e from 3.0.1 until 6.0.2, 5.5.2.2, and 5.2.11.9.\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-204\", \"description\": \"CWE-204 Observable Response Discrepancy\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"The 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. 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      "dataType": "CVE_RECORD",
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    }
  }
}


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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.