GHSA-27mw-82g8-phjj

ghsaUSosv

SvelteKit : XSS via untrusted cache-control header in prerendered page

view advisory published 2026-10-23Licence: CC-BY-4.0

### 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.

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describes (1)

Related CVEs.

IDseverity exploitable
CVE-2026-114061USmedium4.7—
SvelteKit (@sveltejs/kit) before 3.0.0 contains a cross-site scripting vulnerability in prerendered pages because a cache-control header value set via setHeaders is inserted withou…
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