Elysia affected by arbitrary code injection through cookie config

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, '$\\{') + '`' ```

Source published

9 Dec 2025 17:12:05 UTC

Source modified

4 Feb 2026 03:09:32 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · 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

Publisher rating · HIGH