PT-2026-42986 · Npm · Svelte

Published 2026-05-14 · Updated 2026-05-14

OSV

CVSS v4.0

5.3

Medium

Base vector

AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Contents of hydratable promises were not properly stringified, potentially leading to an XSS exploit. You are vulnerable if all of the following is true:

• you are using hydratable (an experimental feature at the time of this report)
• you are passing attacker-controlled input such that a synchronous value is hydrated, then a promise value, e.g. hydratable('someKey', () => [synchronousValue, promiseValue])

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

GHSA-F3CJ-J4F6-WQ85

Affected Products

Svelte

References · 5

• https://osv.dev/vulnerability/GHSA-f3cj-j4f6-wq85 · Vendor Advisory
• https://github.com/sveltejs/svelte · Note
• https://github.com/sveltejs/svelte/commit/a16ebc67bbcf8f708360195687e1b2719463e1a4 · Note
• https://github.com/sveltejs/svelte/security/advisories/GHSA-f3cj-j4f6-wq85 · Note
• http://github.com/sveltejs/svelte/releases/tag/svelte%405.55.7 · Note