Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-40876

Severity CVSS v4.0:
HIGH
Type:
CWE-22 Path Traversal
Publication date:
21/04/2026
Last modified:
24/04/2026

Description

goshs is a SimpleHTTPServer written in Go. Prior to 2.0.0-beta.6, goshs contains an SFTP root escape caused by prefix-based path validation. An authenticated SFTP user can read from and write to filesystem paths outside the configured SFTP root, which breaks the intended jail boundary and can expose or modify unrelated server files. The SFTP subsystem routes requests through sftpserver/sftpserver.go into DefaultHandler.GetHandler() in sftpserver/handler.go, which forwards file operations into readFile, writeFile, listFile, and cmdFile. All of those sinks rely on sanitizePath() in sftpserver/helper.go. helper.go uses a raw string-prefix comparison, not a directory-boundary check. Because of that, if the configured root is /tmp/goshsroot, then a sibling path such as /tmp/goshsroot_evil/secret.txt incorrectly passes validation since it starts with the same byte prefix. This vulnerability is fixed in 2.0.0-beta.6.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 8.70 HIGH
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): Low
User Interaction (UI): None
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
8.70
Severity 4.0
HIGH
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 8.80 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x
8.80
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:goshs:goshs:*:*:*:*:*:go:*:* 2.0.0 (excluding)
cpe:2.3:a:goshs:goshs:2.0.0:beta1:*:*:*:go:*:*
cpe:2.3:a:goshs:goshs:2.0.0:beta2:*:*:*:go:*:*
cpe:2.3:a:goshs:goshs:2.0.0:beta3:*:*:*:go:*:*
cpe:2.3:a:goshs:goshs:2.0.0:beta4:*:*:*:go:*:*
cpe:2.3:a:goshs:goshs:2.0.0:beta5:*:*:*:go:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools