CVE-2026-82259

High

Description

SvelteKit versions from 2.49.0 through 2.53.2 (fixed in 2.53.3) contain a deserialization expansion issue in the experimental form remote function. When an application enables experimental.remoteFunctions and uses the form function to process the files array without validating files.length or individual file sizes, an attacker can submit relatively small inputs that expand into very large file arrays, leading to expensive processing and denial of service.

SeverityHigh

CVSS7.5

Exploit probability—

Product

Sveltekit

PublishedAug 28, 2026

First seenAug 28, 2026

Weakness typeCWE-502Deserialization of untrusted data

How to fix

Update

svelte sveltekit2.53.3 or later
@sveltejs/kit2.53.3 or later

Vendor advisories

github.com/sveltejs/kit/security/advisories/GHSA-fpg4-jhqr-589c

Affected products

Product	Affected versions	Fixed in
svelte sveltekit	2.49.0 ≤ v < 2.53.3	2.53.3
@sveltejs/kitnpm	2.49.0 ≤ v < 2.53.3	2.53.3

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