CVE-2026-27118CWE-346

Cache poisoning in @sveltejs/adapter-vercel

Medium · published February 20, 2026

CVSS v4.0
5.3
EPSS
0%
Percentile
15.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
5.3 · MEDIUM
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
EPSS
0.00249 · 15.3th percentile
Weakness
CWE-346 · Origin Validation Error
Published
2026-02-20T21:24Z
EPSS history
Timeline
  • 20 FEB 21:24Z
    Cache poisoning in @sveltejs/adapter-vercel
    cvelistv5