SvelteKit: Path traversal in vite preview server on Windows
Summary
The vite preview server of SvelteKit (@sveltejs/kit) contains a path traversal flaw on Windows in versions 2.10.0 up to, but not including, 3.0.0. An unauthenticated attacker who can reach the preview server over the network or through a tunnel can read files outside the prerendered output directory, such as source code, configuration files or credentials readable by the server process. According to the vendor, development servers, production adapters and preview servers on other operating systems are not affected.
Affected
- @sveltejs/kit 2.10.0 up to, but not including, 3.0.0
- Preview server (vite preview) running on Windows
Fixed in
- @sveltejs/kit 3.0.0 or later
Workaround
- Keep the preview server bound to localhost and do not use the --host flag or preview.host configuration
- Remove public tunnels to the preview server
- Restrict network access to the preview server
- Running the preview server on a non-Windows operating system also avoids the vulnerability
Exploitation
- CISA SSVC: exploitation none, automatable yes, technical impact partial
- Not marked as known exploited at time of research
- No public proof of concept found in our research; this does not rule one out
Our recommendation
- Upgrade @sveltejs/kit to 3.0.0 or later
- Until the upgrade, do not expose vite preview to networks or tunnels, and do not use it as a production server
- Check Windows hosts, developer machines, staging servers and CI systems for preview scripts with --host or a public tunnel
- Treat exposed Windows preview hosts as high priority, because exposed credentials could enable further compromise
- Note that GitHub labels the advisory Moderate while the CVSS 4.0 score is 8.7; use the CVSS score for prioritization
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-xgrj-p7pg-6vm3 github.com
- VulnCheck advisory www.vulncheck.com
- SvelteKit 3.0.0 release notes github.com
- OpenCVE CVE-2026-114063 app.opencve.io
- HOL Guard CVE-2026-114063 hol.org
- Strix CVE-2026-114063 www.strix.ai
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 01:11.
Original description (NVD)
SvelteKit (@sveltejs/kit) from 2.10.0 before 3.0.0 contains a path traversal vulnerability in the vite preview server on Windows that allows unauthenticated attackers to read files outside the prerendered output directory. Attackers who can reach the preview server through network access or a tunnel can send crafted requests to expose source code, configuration, or credentials readable by the server process.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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