CVE-2026-23942 | SFTP root escape via component-agnostic prefix check in ssh_sftpd

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2. The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root. This issue affects OTP from OTP 17.0 until OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 until 5.5.1, 5.2.11.6 and 5.1.4.14.

Published: 2026-03-13 Last update: 2026-05-21 Assigner: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-23942 is rated Low Risk (22.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-23942

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-13 — 0.02% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23942

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 4.0 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:L)
Low privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:L)
Limited confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:L)
Limited integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.5 [email protected]

Weakness enumeration for CVE-2026-23942

OS Trackers for CVE-2026-23942

vendor priority summary link
debian not yet assigned CVE-2026-23942 not yet assigned priority: Debian including 1 source packages (erlang), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-23942
suse medium — https://www.suse.com/security/cve/CVE-2026-23942/
ubuntu medium CVE-2026-23942 medium priority: Ubuntu including 1 source packages (erlang), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 8. https://ubuntu.com/security/CVE-2026-23942

Affected software / configurations for CVE-2026-23942

Vendor Product Version Raw CPE
erlang erlang\/otp >= 17.0, < 26.2.5.18 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
erlang erlang\/otp >= 27.0, < 27.3.4.9 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
erlang erlang\/otp >= 28.0, < 28.4.1 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
erlang erlang\/ssh >= 3.0.1, < 5.1.4.14 cpe:2.3:a:erlang:erlang\/ssh:*:*:*:*:*:*:*:*
erlang erlang\/ssh >= 5.2, < 5.2.11.6 cpe:2.3:a:erlang:erlang\/ssh:*:*:*:*:*:*:*:*
erlang erlang\/ssh >= 5.5, <= 5.5.1 cpe:2.3:a:erlang:erlang\/ssh:*:*:*:*:*:*:*:*

References for CVE-2026-23942

cvelogic Threat Intelligence