CVE-2026-8023
HIGH · 7.5Published advisory + technical confirmation + vendor response; no in-the-wild exploitation confirmed yet.
What: Path traversal in Zephyr RTOS HTTP server static-filesystem handler (CVE-2026-8023, CVSS 7.5) allows unauthenticated remote arbitrary file read via unresolved ../ segments in request URLs; affects versions 4.0.0–4.4.0 with CONFIG_FILE_SYSTEM enabled.
Why it matters: Published 29 June 2026; no KEV listing yet but NVD description confirms working vulnerability (missing canonicalization in http_server_remove_dot_segments() code path), confirmed patch available. Zephyr IoT/embedded deployments exposed without authentication required.
Where it's seen: Real-time Bluesky chatter from security engineers (same day publication), threat radar indexing, vendor advisory circulation beginning. No public PoC exploit code yet in snippets.
RISK: HIGH — Unauthenticated remote file disclosure in widely-deployed embedded HTTP stack; patch available but adoption lag likely.
Description
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.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N- Attack vector
- Network
- Complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None