SvelteKit : XSS via untrusted cache-control header in prerendered page
Impact
Applications that prerender pages and use setHeaders to set a cache-control header from an untrusted source are vulnerable to cross-site scripting (XSS).
SvelteKit inserts the header value into a <meta http-equiv="cache-control"> tag without escaping it. An attacker who can influence this value at prerender time can break out of the content attribute and inject HTML or JavaScript into the generated page. The injected code can then execute when users visit the page.
Patches
The fix escapes the header value before inserting it into the generated HTML. Upgrade to @sveltejs/kit version 3.0.0 or later.
Workarounds
Avoid forwarding untrusted cache-control header values with setHeaders on prerendered pages. Use a fixed, trusted cache policy instead.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @sveltejs/kit | < 3.0.0 | 3.0.0 |
References
- https://github.com/sveltejs/kit/security/advisories/GHSA-27mw-82g8-phjj
- https://nvd.nist.gov/vuln/detail/CVE-2026-114061
- https://github.com/sveltejs/kit/commit/d9d55b579743c80ee7cb59c272d864fd9253dae7
- https://github.com/sveltejs/kit
- https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@3.0.0
- https://www.vulncheck.com/advisories/sveltekit-before-3.0.0-xss-via-cache-control-header-in-prerendered-pages
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
@sveltejs/kit- Disclosed
- 23.10.2026
- Updated
- 24.10.2026 00:17
Sources and licenses
OSV / GitHub Advisory Database - GHSA-27mw-82g8-phjj - CC BY 4.0
Vulnerability history: @sveltejs/kit
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 19
- First → latest
- 04.2023 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 6
- Medium 8
- Low 5
Disclosures per year
- 2023: 2
- 2024: 3
- 2025: 1
- 2026: 13
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SvelteKit : XSS via untrusted cache-control header in prerendered page this entry
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