CVE-2025-66457: Elysia Elysia Affected By Arbitrary Code Vulnerability
HIGHCVE-2025-66457 is a HIGH elysia affected by arbitrary code vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Elysia libraries in the npm ecosystem. The issue involves elysia affected by arbitrary code injection through cookie config. Remediation is available by upgrading affected packages to version 1.4.18.
CVE-2025-66457 at a Glance
How to Fix CVE-2025-66457
To remediate this vulnerability, upgrade all affected Elysia dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install elysia@1.4.18Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls elysiaHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2025-66457, inspect your project dependencies using npm:
npm ls elysiaAnalyze the terminal output to locate any version of Elysia in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.4.18), your application is affected.
Note: The npm ls elysia command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Elysia, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2025-66457 Affected Elysia Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
elysia
|
npm |
< 1.4.18
|
1.4.18
|
References
Frequently Asked Questions
What is CVE-2025-66457?
Which Elysia versions are affected?
What version fixes CVE-2025-66457?
Is elysia affected?
What CWE is associated with CVE-2025-66457?
How can I check npm dependencies for CVE-2025-66457?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-8vch-m3f4-q8jf",
"modified" : "2025-12-09T21:37:17Z",
"published" : "2025-12-09T17:12:05Z",
"aliases" : [ "CVE-2025-66457" ],
"summary" : "Elysia affected by arbitrary code injection through cookie config",
"details" : "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.\n\nAvailability 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). \n\nHowever when combined with GHSA-hxj9-33pp-j2cc, this vulnerability allows for a full RCE chain.\n\n### Impact\n- aot enabled (default)\n- cookie schema passed to route\n- Cookie config controllable eg. via env\n\nExample of vulnerable code\n```js\nnew Elysia({\n\tcookie: {\n\t\tsecrets: `' + console.log('pwned from secrets') + '`\n\t},\n})\n\t.get(\"/\", () => \"hello world\", {\n\t\tcookie: t.Cookie({\n\t\t\tfoo: t.Any(),\n\t\t}),\n\t})\n```\n\nPOC: https://github.com/sportshead/elysia-poc\n\n### Patches\nPatched by 1.4.17 (https://github.com/elysiajs/elysia/pull/1564)\n\nReference commit:\n- https://github.com/elysiajs/elysia/pull/1564/commits/26935bf76ebc43b4a43d48b173fc853de43bb51e\n- https://github.com/elysiajs/elysia/pull/1564/commits/3af978663e437dccc6c1a2a3aff4b74e1574849e\n\n### Workarounds\nSanitize cookie-related env input\n\n```typescript\nconst overrideUnsafeQuote = (value: string) =>\n\t// '`' + value + '`'\n\t'`' + value.replace(/'/g, '\\\\`').replace(/\\${/g, '$\\\\{') + '`'\n```",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "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"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "elysia"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.4.18"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf"
}, {
"type" : "WEB",
"url" : "https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-66457"
}, {
"type" : "WEB",
"url" : "https://github.com/elysiajs/elysia/pull/1564"
}, {
"type" : "WEB",
"url" : "https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e"
}, {
"type" : "WEB",
"url" : "https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/elysiajs/elysia"
}, {
"type" : "WEB",
"url" : "https://github.com/sportshead/elysia-poc"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-94" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2025-12-09T17:12:05Z",
"nvd_published_at" : "2025-12-09T20:15:54Z"
}
}