How severe is GHSA-fpg4-jhqr-589c?

No CVSS score has been assigned to GHSA-fpg4-jhqr-589c yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-fpg4-jhqr-589c?

GHSA-fpg4-jhqr-589c affects the following packages: @sveltejs/kit (npm). Ecosystems affected: npm.

How do I fix GHSA-fpg4-jhqr-589c?

Update @sveltejs/kit to 2.53.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fpg4-jhqr-589c is resolved across your whole dependency graph.

How do I detect GHSA-fpg4-jhqr-589c in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sveltejs/kit. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-fpg4-jhqr-589c if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-fpg4-jhqr-589c?

O3 pinpoints whether GHSA-fpg4-jhqr-589c is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-fpg4-jhqr-589c actively exploited in the wild?

No public exploit code has been indexed for GHSA-fpg4-jhqr-589c yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-fpg4-jhqr-589c published, and has it been updated?

GHSA-fpg4-jhqr-589c was published on February 28, 2026 and was last updated on February 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

GHSA-fpg4-jhqr-589c

GHSA-fpg4-jhqr-589c is a security vulnerability in @sveltejs/kit. O3 Security confirms whether GHSA-fpg4-jhqr-589c is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

SvelteKit has deserialization expansion in unvalidated `form` remote function leading to Denial of Service (experimental only)

Published

Feb 28, 2026

Updated

Feb 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

@sveltejs/kitnpm

2.4Mdownloads / week

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@sveltejs/kit`	≥ 2.49.0&&< 2.53.3	2.53.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sveltejs/kit. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @sveltejs/kit to 2.53.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fpg4-jhqr-589c is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-fpg4-jhqr-589c is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-fpg4-jhqr-589c. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is GHSA-fpg4-jhqr-589c in your dependencies?

O3 detects GHSA-fpg4-jhqr-589c across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works