CVE-2026-56669

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to 1.4.29, Elysia uses getAll in form data normalization for multipart/form-data endpoints, causing the amount of work to grow quadratically with the number of unique key-value pairs and allowing CPU exhaustion. This issue is fixed in version 1.4.29.

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to 1.4.29, Elysia uses getAll in form data normalization for multipart/form-data endpoints, causing the amount of work to grow quadratically with the number of unique key-value pairs and allowing CPU exhaustion. This issue is fixed in version 1.4.29.

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 form data normalizer has to scan n x n key-value pairs.

Impact

Endpoints using multipart/form-data

Patches

1.4.29

Workarounds

no 100% confirm workaround beside updating the patch

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to 1.4.29, Elysia uses getAll in form data normalization for multipart/form-data endpoints, causing the amount of work to grow quadratically with the number of unique key-value pairs and allowing CPU exhaustion. This issue is fixed in version 1.4.29.

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to 1.4.29, Elysia uses getAll in form data normalization for multipart/form-data endpoints, causing the amount of work to grow quadratically with the number of unique key-value pairs and allowing CPU exhaustion. This issue is fixed in version 1.4.29.

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 form data normalizer has to scan n x n key-value pairs.

Impact

Endpoints using multipart/form-data

Patches

1.4.29

Workarounds

no 100% confirm workaround beside updating the patch