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 26.2.5.20, OTP 27.3.4.11, and OTP 28.4.3, corresponding to ssh from 3.0.1 before 5.1.4.15, 5.2.11.7, and 5.5.2. Whether OTP before OTP 17.0, corresponding to ssh before 3.0.1, is affected is unknown.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (4.3): severity, escalated by confirmed exploitation. This CVE's 4.3 is its impact severity (EG Severity), not escalated.
- EG Severity
- 4.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it