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CVE-2026-8023

Path traversal in Zephyr HTTP server static-filesystem resource handler allows unauthenticated remote arbitrary file read

publishedCWE-22CWE-23

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.

Technical severity7.5 highCVSS 3.1 · CNA: zephyr
Published2026-06-29Source updated 2026-11-04
Collected2026-11-043 attributed sources

Fixes and workarounds

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: CNA: zephyr

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: [email protected]

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: [email protected]

Fix

The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Affected products and versions

ProductVersionsAuthority
zephyr
zephyrproject
zephyr
https://github.com/zephyrproject-rtos/zephyr 		≥ 4.0.0; < 4.6.0 (affected, semver)
Other versions: unaffected 		CNA: zephyr

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

NVD applicability configurations (1)

These expressions retain AND/OR operators, negation, and required environmental products. A listed product is not sufficient to establish exposure when additional conditions apply.

[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:*",
            "versionEndIncluding": "4.4.1",
            "versionStartIncluding": "4.0.0",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]

CVSS assessments

Version / scoreVectorAuthority
3.1 / 7.5
high		 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NCNA: zephyr
3.1 / 7.5
high		 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NNVD: [email protected]

Exploit evidence

References

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