GHSA-hxj9-33pp-j2cc — elysia
Fix: elysiajs/elysia#1564GHSA-hxj9-33pp-j2cc is a CWE-1321 vulnerability in elysia. A fix is available for elysia — see the affected versions and patch details below.
Elysia vulnerable to prototype pollution with multiple standalone schema validation
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hxj9-33pp-j2cc.
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.
elysianpmDescription
Prototype pollution vulnerability in mergeDeep after merging results of two standard schema validations with the same key. Due to the ordering of merging, there must be an any type that is set as a standalone guard, to allow for the __proto__ prop to be merged.
When combined with GHSA-8vch-m3f4-q8jf this allows for a full RCE by an attacker.
Impact
Routes with more than 2 standalone schema validation, eg. zod
Example vulnerable code:
import { Elysia } from "elysia"
import * as z from "zod"
const app = new Elysia()
.guard({
schema: "standalone",
body: z.object({
data: z.any()
})
})
.post("/", ({ body }) => ({ body, win: {}.foo }), {
body: z.object({
data: z.object({
messageId: z.string("pollute-me"),
})
})
})
Patches
Patched by 1.4.17 (https://github.com/elysiajs/elysia/pull/1564)
Reference commit:
- https://github.com/elysiajs/elysia/pull/1564/commits/26935bf76ebc43b4a43d48b173fc853de43bb51e
- https://github.com/elysiajs/elysia/pull/1564/commits/3af978663e437dccc6c1a2a3aff4b74e1574849e
Workarounds
Remove __proto__ key from body
Example plugin for removing __proto__ from body
new Elysia()
.onTransform(({ body, headers }) => {
if (headers['content-type'] === 'application/json')
return JSON.parse(JSON.stringify(body), (k, v) => {
if (k === '__proto__') return
return v
})
})
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | elysia | ≥ 1.4.0&&< 1.4.17 | 1.4.17npm install elysia@1.4.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for elysia, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update elysia to 1.4.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hxj9-33pp-j2cc 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-hxj9-33pp-j2cc can be triaged on real exposure rather than presence alone.
Tailored to GHSA-hxj9-33pp-j2cc. 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-hxj9-33pp-j2cc in your dependencies?
O3 Security finds GHSA-hxj9-33pp-j2cc across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.