# CVE-2026-16653: boazsegev facil.io path traversal in Public Folder Handler

Source: https://junglewise.ai/threats/cve-2026-16653-boazsegev-facil-io-path-traversal-in-public-folder-handler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-23. Updated: 2026-07-23  
License: CC BY 4.0 with a link back

CVE-2026-16653 · Severity: medium · CVSS 5.3 · Published 2026-07-23

facil.io is a high-performance web application framework for the C programming language. A security flaw in its static file handler allows remote attackers to access files outside of the designated public folder. This could lead to the exposure of sensitive information, such as configuration files, application source code, or system logs, depending on the server's permissions.

Technologies: [Boaz Segev Facil.Io](https://junglewise.ai/threats/technologies/facil-io). Vendors: [Boaz Segev](https://junglewise.ai/threats/vendors/boaz-segev).

## Quick answers

**Is CVE-2026-16653 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-16653 being exploited in the wild.

**How severe is CVE-2026-16653?** Medium severity, with a CVSS score of 5.3, published 23 July 2026.

**Which products and versions are affected?** Boaz Segev Facil.Io up to 0.7.58.

**Is there a fix for CVE-2026-16653?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-16653 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-16653?** Check whether you run Boaz Segev Facil.Io at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A path traversal vulnerability exists in the facil.io web framework when the .public_folder configuration is enabled. The vulnerability resides in the http_sendfile2 function within lib/facil/http/http.c. While the framework uses http_test_encoded_path() to detect traversal sequences like '/../', it fails to validate request paths that begin directly with '../'. Because the HTTP/1 parser accepts request targets that do not start with a forward slash, an unauthenticated remote attacker can craft a GET request (e.g., 'GET ../secret.txt') to escape the intended static file root. This allows for the unauthorized reading of arbitrary files accessible to the server process. As of the advisory date, no patch has been released.

## Affected products

- boazsegev facil.io up to 0.7.58

## Timeline

- 2026-06-17: disclosed: Issue reported via GitHub issue #170
- 2026-07-23: advisory: CVE published and added to NVD

## References

- [https://github.com/boazsegev/facil.io/](https://github.com/boazsegev/facil.io/)
- [https://github.com/boazsegev/facil.io/issues/170](https://github.com/boazsegev/facil.io/issues/170)
- [https://vuldb.com/cve/CVE-2026-16653](https://vuldb.com/cve/CVE-2026-16653)
- [https://vuldb.com/submit/860587](https://vuldb.com/submit/860587)
- [https://vuldb.com/vuln/382396](https://vuldb.com/vuln/382396)
- [https://vuldb.com/vuln/382396/cti](https://vuldb.com/vuln/382396/cti)

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