CVE-2026-27734

Received Received - Intake

Path Traversal in Beszel API Allows Docker Endpoint Exposure

Publication date: 2026-02-27

Last updated on: 2026-03-04

Assigner: GitHub, Inc.

Description

Beszel is a server monitoring platform. Prior to version 0.18.2, the hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied "container" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize `../` sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details. Version 0.18.4 fixes the issue.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-02-27

Last Modified

2026-03-04

Generated

2026-07-06

AI Q&A

2026-02-27

EPSS Evaluated

2026-07-05

NVD

CVE-2026-27734

EUVD

EUVD-2026-9053

Affected Vendors & Products

Vendor	Product	Version / Range
beszel	beszel	to 0.18.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-22	The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

Impact Analysis

An attacker who is authenticated, including those with readonly roles, can exploit this vulnerability to traverse to arbitrary Docker API endpoints on the agent hosts. This unauthorized access can expose sensitive infrastructure details, potentially revealing critical information about the monitored environment. Such exposure can lead to further attacks or compromise of the infrastructure.

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade Beszel to version 0.18.4 or later, where the issue has been fixed.

Executive Summary

This vulnerability exists in the Beszel server monitoring platform prior to version 0.18.2. The issue is that the authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info accept a user-supplied "container" query parameter without validating it. The agent then uses this raw value to construct Docker Engine API URLs without proper escaping. Because Go's http.Client does not sanitize "../" sequences in URL paths sent over unix sockets, an authenticated user, even with readonly role, can perform directory traversal to access arbitrary Docker API endpoints on the agent hosts. This can expose sensitive infrastructure details. The issue was fixed in version 0.18.4.

Compliance Impact

I don't know

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