GHSA-j2f3-wq62-6q46 — @sveltejs/kit
Fix: sveltejs/kit@8ed8155GHSA-j2f3-wq62-6q46 is a CWE-789 vulnerability in @sveltejs/kit. A fix is available for @sveltejs/kit — see the affected versions and patch details below.
@sveltejs/kit has memory amplification DoS vulnerability in Remote Functions binary form deserializer (application/x-sveltekit-formdata)
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-j2f3-wq62-6q46.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@sveltejs/kitnpmDescription
Summary
The experimental form remote function uses a binary data format containing a representation of submitted form data. A specially-crafted payload can cause the server to allocate a large amount of memory, causing DoS via memory exhaustion.
Details
When a form is submitted to a remote function endpoint, the SvelteKit client encodes the data using a custom format, and POSTs it to the endpoint as a request with an application/x-sveltekit-formdata content type.
The first few bytes of the request body encode the length of the data. SvelteKit will attempt to read the request body up until the specified offset, but if the body is not yet available then an array buffer of that size will be created eagerly to accommodate it as it arrives.
An attacker can force this code path by sending a small payload that specifies a large data length, then stalling the connection. The resulting array buffer will be held in memory, potentially causing memory exhaustion.
Impact
- Vulnerability type: Availability / memory exhaustion (memory amplification).
- Who is impacted: SvelteKit apps with
experimental.remoteFunctionsenabled, and that expose a reachable Remote Form endpoint. - Attack: an unauthenticated attacker can repeatedly open connections, send only the 8-byte header/prefix (with large data_length), and stall the body to hold large allocations, exhausting memory.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @sveltejs/kit | ≥ 2.49.0&&< 2.49.5 | 2.49.5npm install @sveltejs/kit@2.49.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sveltejs/kit, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @sveltejs/kit to 2.49.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j2f3-wq62-6q46 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-j2f3-wq62-6q46 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-j2f3-wq62-6q46. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-j2f3-wq62-6q46 in your dependencies?
O3 Security finds GHSA-j2f3-wq62-6q46 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.