GHSA-fpg4-jhqr-589c: @sveltejs/kit Denial of Service Vulnerability

LOW
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CWE-770
Published
Advisory Summary

GHSA-fpg4-jhqr-589c is a LOW denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting @sveltejs/kit libraries in the npm ecosystem. The issue involves sveltekit has deserialization expansion in unvalidated `form` remote function leading to denial of service (experimental only). Remediation is available by upgrading affected packages to version 2.53.3.

GHSA-fpg4-jhqr-589c at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-fpg4-jhqr-589c
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product @sveltejs/kit
Package Ecosystem npm
Published Date
Last Updated

How to Fix GHSA-fpg4-jhqr-589c

To remediate this vulnerability, upgrade all affected @sveltejs/kit dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@sveltejs/kit fixed: 2.53.3 
npm install @sveltejs/kit@2.53.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @sveltejs/kit

How to Check if You Are Affected

To determine whether your Node.js application is affected by GHSA-fpg4-jhqr-589c, inspect your project dependencies using npm:

npm ls @sveltejs/kit

Analyze the terminal output to locate any version of @sveltejs/kit in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.53.3), your application is affected.

Note: The npm ls @sveltejs/kit command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In @sveltejs/kit, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Some relatively small inputs can cause very large files arrays in `form` handlers. If the SvelteKit application code doesn't check `files.length` or individual files' sizes and performs expensive processing with them, it can result in Denial of Service. Only users with `experimental.remoteFunctions: true` who are using the `form` function and are processing the `files` array without validation are vulnerable.

GHSA-fpg4-jhqr-589c Affected @sveltejs/kit Versions

1 component(s)
Fixed Versions:
2.53.3
Product / Package Ecosystem Affected Versions Fixed Version
@sveltejs/kit
npm/@sveltejs/kit
npm
≥ 2.49.0
< 2.53.3
2.53.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/sveltejs/kit/security/advisories/GHSA-fpg4-jhqr-589c
Security Fix Commit FIX COMMIT
https://github.com/sveltejs/kit/commit/faba869db3644077169bf5d7c6e41fd5f3d6c65e
@sveltejs/kit Source Repository REPOSITORY
https://github.com/sveltejs/kit
@sveltejs/kit Release RELEASE
https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@2.53.3

Frequently Asked Questions

What is GHSA-fpg4-jhqr-589c?
GHSA-fpg4-jhqr-589c is a security vulnerability in @sveltejs/kit involving SvelteKit has deserialization expansion in unvalidated `form` remote function leading to Denial of Service (experimental only) under CWE-770: Allocation of Resources Without Limits or Throttling.
Which @sveltejs/kit versions are affected?
Affected versions include releases prior to 2.53.3 across affected packages: @sveltejs/kit.
What version fixes GHSA-fpg4-jhqr-589c?
Upgrading to 2.53.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @sveltejs/kit affected?
Yes, @sveltejs/kit is affected in releases prior to 2.53.3. Upgrade your dependency to 2.53.3 or later.
What CWE is associated with GHSA-fpg4-jhqr-589c?
GHSA-fpg4-jhqr-589c is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check npm dependencies for GHSA-fpg4-jhqr-589c?
Run the dependency tree command: 'npm ls @sveltejs/kit'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fpg4-jhqr-589c",
  "modified" : "2026-02-28T02:04:39Z",
  "published" : "2026-02-28T02:04:39Z",
  "aliases" : [ ],
  "summary" : "SvelteKit  has deserialization expansion in unvalidated `form` remote function leading to Denial of Service (experimental only)",
  "details" : "Some relatively small inputs can cause very large files arrays in `form` handlers. If the SvelteKit application code doesn't check `files.length` or individual files' sizes and performs expensive processing with them, it can result in Denial of Service.\n\nOnly users with `experimental.remoteFunctions: true` who are using the `form` function and are processing the `files` array without validation are vulnerable.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@sveltejs/kit"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.49.0"
      }, {
        "fixed" : "2.53.3"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.53.2"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/sveltejs/kit/security/advisories/GHSA-fpg4-jhqr-589c"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sveltejs/kit/commit/faba869db3644077169bf5d7c6e41fd5f3d6c65e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/sveltejs/kit"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@2.53.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-28T02:04:39Z",
    "nvd_published_at" : null
  }
}