elysia

Elysia v1.4.28 is vulnerable to denial-of-service attacks due to CPU exhaustion in the form data normalization code. Elysia uses `getAll` to retrieve value from FormData. It is called directly relative to the total number of key-value pairs in the form data. The total amount of work the for loop has to do grows quadratically, so doubling the number of unique key-value pairs quadruples the amount of work. In the above PoC, each .getAll call scans through all of the `n` key-value pairs in the form data. Because there are `n` unique keys in the form data, there are .getAll calls, so in total the

CVE: CVE-2026-56669

### Impact Elysia cookie can be overridden by prototype pollution , eg. `__proto__` Sending cookie with the follows name can override cookie value: ```bash __proto__=%7B%22injected%22%3A%22polluted%22%7D ``` ### Patches Patched by 1.4.27 ### Workarounds 1. Use t.Cookie validation to enforce validation value 2. Prevent iterable over cookie if possible

CVE: CVE-2026-31865

### Impact `t.String({ format: 'url' })` is vulnerable to redos Repeating a partial url format (protocol and hostname) multiple times cause regex to slow down significantly ```js 'http://a'.repeat(n) ``` Here's a table demonstrating how long it takes to process repeated partial url format | `n` repeat | elapsed_ms | | --- | --- | | 1024 | 33.993 | | 2048 | 134.357 | | 4096 | 537.608 | | 8192 | 2155.842 | | 16384 | 8618.457 | | 32768 | 34604.139 | ### Patches Patched by 1.4.26, please kindly update `elysia` to >= 1.4.26 Here's how long it takes after the patch | `n` repeat | elapsed_ms | |

CVE: CVE-2026-30837

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 (defau

CVE: CVE-2025-66457

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: ```typescript import { Elysia } from "elysia" import * as z from "zod" const app = new Elysia() .guard({ schema: "standalone", body: z.object

CVE: CVE-2025-66456