GitHub Advisoryadvisory · npm
GHSA-8vch-m3f4-q8jf Elysia affected by arbitrary code injection through cookie config
HIGH
Official page ↗
- Aliases
- CVE-2025-66457
- Ecosystem
- npm
- Packages
- elysia
- Severity
- High
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Weaknesses
- CWE-94
- Reviewed
- 2025-12-09
Affected packages
• npm elysia: < 1.4.18 → fixed in 1.4.18
Description
Arbitrary code execution from cookie config. If dynamic cookies are enabled (ie there exists a schema for cookies), the cookie config is injected into the compiled route without first being sanitised.
Availability of this exploit is generally low, as it requires write access to either the Elysia app's source code (in which case the vulnerability is meaningless) or write access to the cookie config (perhaps where it is assumed to be provisioned by the environment).
However when combined with GHSA-hxj9-33pp-j2cc, this vulnerability allows for a full RCE chain.
Impact
• aot enabled (default)
• cookie schema passed to route
• Cookie config controllable eg. via env
Example of vulnerable code
```js
new Elysia({
cookie: {
secrets: `' + console.log('pwned from secrets') + '`
},
})
.get("/", () => "hello world", {
cookie: t.Cookie({
foo: t.Any(),
}),
})
```
POC: https://github.com/sportshead/elysia-poc
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
Sanitize cookie-related env input
```typescript
const overrideUnsafeQuote = (value: string) =>
// '`' + value + '`'
'`' + value.replace(/'/g, '\\`').replace(/\${/g, '$\\{') + '`'
```
Related
Alias · CVE (1)
- CVE-2025-66457 Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. vulnerability
Weakness · CWE (1)
- CWE-94 Improper Control of Generation of Code weakness
References
- https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf web
- https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc web
- https://nvd.nist.gov/vuln/detail/CVE-2025-66457 advisory
- https://github.com/elysiajs/elysia/pull/1564 web
- https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e web
- https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e web
- https://github.com/elysiajs/elysia package
- https://github.com/sportshead/elysia-poc web