Vulnerability · Published Feb 20, 2026 · Assigned by GitHub_M
CVE-2026-27118Cache poisoning in @sveltejs/adapter-vercel
Medium 5.3
In plain English
A medium-severity security flaw in kit from sveltejs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 20% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Versions of @sveltejs/adapter-vercel prior to 6.3.2 are vulnerable to cache poisoning. An internal query parameter intended for Incremental Static Regeneration (ISR) is accessible on all routes, allowing an attacker to cause sensitive user-specific responses to be cached and served to other users. Successful exploitation requires a victim to visit an attacker-controlled link while authenticated. Existing deployments are protected by Vercel's WAF, but users should upgrade as soon as possible. This vulnerability is fixed in 6.3.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @sveltejs/adapter-vercel | 6.3.2 | GHSA-9pq4-5hcf-288c |
Affected products (as reported)
Weakness: CWE-346 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/sveltejs/kit/security/advisories/GHSA-9pq4-5hcf-288c x_refsource_CONFIRM