CVE-2026-8023
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.87%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.87% probability · 59th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-22, CWE-23
- Affected
- zephyrproject/zephyr
- Source
- vulnerabilities@zephyrproject.org
EPSS 0.9% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/zephyrproject-rtos/zephyr/commit/f4a423c98554f209c5d2f22f041822422c9263b8Patch
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hch3-53g6-jj3hExploit, Patch, Vendor Advisory
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hch3-53g6-jj3hExploit, Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.