zephyrproject zephyr up to 4.4.x FS Handler /net/lib/http on_url path traversal

Summaryinfo

A vulnerability classified as critical was found in zephyrproject zephyr up to 4.4.x. Affected by this issue is the function on_url of the file /net/lib/http of the component FS Handler. Such manipulation leads to path traversal. This vulnerability is listed as CVE-2026-8023. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in zephyrproject zephyr up to 4.4.x and classified as critical. Affected by this issue is the function on_url of the file /net/lib/http of the component FS Handler. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality. CVE summarizes:

Zephyr's HTTP server (subsys/net/lib/http) provides a static-filesystem resource type (HTTP_RESOURCE_TYPE_STATIC_FS, available when CONFIG_FILE_SYSTEM is enabled) that serves files from a configured root directory. Before this fix, both the HTTP/1 and HTTP/2 front-ends placed the raw, attacker-controlled request path into client-url_buffer (assembled in on_url() for HTTP/1 and copied verbatim from the :path pseudo-header for HTTP/2) without resolving ./.. segments. The static-FS handler then built the on-disk filename by directly concatenating the configured root with that raw URL (snprintk(fname, ..., "%s%s", static_fs_detail-fs_path, client-url_buffer) at http_server_http1.c:603 and http_server_http2.c:490) and opened it with fs_open(fname, FS_O_READ). Because the handler is reached via wildcard/leading-dir (fnmatch FNM_LEADING_DIR) or fallback resource matching, a request such as GET /<prefix/../../<file is dispatched to the handler and, after the underlying filesystem (e.g. LittleFS/FAT) resolves the .. segments, escapes the configured web root, letting an unauthenticated remote client read arbitrary readable files on the mounted volume (information disclosure). The HTTP server requires no TLS or authentication to reach this path. The fix adds http_server_remove_dot_segments(), which canonicalizes the path portion of the URL before resource lookup in both protocol handlers, neutralizing the traversal. Affects releases v4.0.0 through v4.4.0 for deployments that register a static-filesystem resource.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-8023 since 05/06/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1006 by the MITRE ATT&CK project.

Upgrading to version 4.5.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-40238). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Project Management Software

Vendor

• zephyrproject

Name

• zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4

CPE 2.3info

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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