GHSA-g5m6-hxpp-fc49 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in @sveltejs/kit. 1 public exploit reference exists, so weaponization risk is real. A fix is available for @sveltejs/kit — see the affected versions and patch details below.
Sending a GET or HEAD request with a body crashes SvelteKit
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-g5m6-hxpp-fc49.
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.
How urgent is this, really
GHSA-g5m6-hxpp-fc49 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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/kitnpm@sveltejs/adapter-nodenpmDescription
Summary
In SvelteKit 2 sending a GET request with a body eg {} to a SvelteKit app in preview or with adapter-node throws Request with GET/HEAD method cannot have body. and crashes the app.
node:internal/deps/undici/undici:6066
throw new TypeError("Request with GET/HEAD method cannot have body.");
^
TypeError: Request with GET/HEAD method cannot have body.
at new Request (node:internal/deps/undici/undici:6066:17)
at getRequest (file:///C:/Users/admin/Desktop/reproduction/node_modules/@sveltejs/kit/src/exports/node/index.js:107:9)
at file:///C:/Users/admin/Desktop/reproduction/node_modules/@sveltejs/kit/src/exports/vite/preview/index.js:181:26
at call (file:///C:/Users/admin/Desktop/reproduction/node_modules/vite/dist/node/chunks/dep-9A4-l-43.js:44795:7)
at next (file:///C:/Users/admin/Desktop/reproduction/node_modules/vite/dist/node/chunks/dep-9A4-l-43.js:44739:5)
at file:///C:/Users/admin/Desktop/reproduction/node_modules/@sveltejs/kit/src/exports/vite/preview/index.js:172:6
at call (file:///C:/Users/admin/Desktop/reproduction/node_modules/vite/dist/node/chunks/dep-9A4-l-43.js:44795:7)
at next (file:///C:/Users/admin/Desktop/reproduction/node_modules/vite/dist/node/chunks/dep-9A4-l-43.js:44739:5)
at file:///C:/Users/admin/Desktop/reproduction/node_modules/@sveltejs/kit/src/exports/vite/preview/index.js:211:27
at call (file:///C:/Users/admin/Desktop/reproduction/node_modules/vite/dist/node/chunks/dep-9A4-l-43.js:44795:7)
Node.js v20.11.0
TRACE requests will also cause the app to crash. Prerendered pages and SvelteKit 1 apps are not affected.
PoC
<!-- _Complete instructions, including specific configuration details, to reproduce the vulnerability._ -->First do a fresh install of SvelteKit 2 with the example app. Typescript.
npm run buildnpm run preview- Go to http://localhost:4173 (works)
- curl -X GET -d "{}" http://localhost:4173/bye
- Application crashes and http://localhost:4173 is down
Impact
<!-- _What kind of vulnerability is it? Who is impacted?_ -->Denial of Service for apps using adapter-node
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @sveltejs/kit | ≥ 2.0.0&&< 2.4.3 | 2.4.3npm install @sveltejs/kit@2.4.3 |
| 📦npm | @sveltejs/adapter-node | ≥ 2.0.0&&< 2.1.2 | 2.1.2npm install @sveltejs/adapter-node@2.1.2 |
| 📦npm | @sveltejs/adapter-node | ≥ 3.0.0&&< 3.0.3 | 3.0.3npm install @sveltejs/adapter-node@3.0.3 |
| 📦npm | @sveltejs/adapter-node | ≥ 4.0.0&&< 4.0.1 | 4.0.1npm install @sveltejs/adapter-node@4.0.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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 2.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g5m6-hxpp-fc49 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-g5m6-hxpp-fc49 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-g5m6-hxpp-fc49. 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-g5m6-hxpp-fc49 in your dependencies?
O3 Security finds GHSA-g5m6-hxpp-fc49 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.