Cache poisoning in @sveltejs/adapter-vercel_CVE-2026-27118

5.3 / 10

MEDIUM

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

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.

Basic Information

ID CVE-2026-27118

Source GitHub_M

Published Feb 20, 2026 at 21:24

Affected Product

Vendor sveltejs

Product kit

Version < 6.3.2

Affected Versions sveltejs kit < 6.3.2

CWE Classification

CWE-346

References

github.com /sveltejs/kit/security/advisories/GHSA-9pq4-5hcf-288c

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