Conform, a type-safe form validation library, allows the parsing of nested objects in the form of object.property. From 1.8.0 until 1.19.4, the parseSubmission future API in packages/conform-dom/formdata.ts repeatedly scans FormData or URLSearchParams entries by each unique field name. An unauthenticated attacker can submit a crafted form containing many unique names, causing excessive synchronous CPU work and denial of service in an application that passes the submission to parseSubmission. Applications should continue to enforce request parsing limits before invoking Conform. This issue is fixed in version 1.19.4.

Affected: npm: @conform-to/dom

A CPU exhaustion vulnerability exists in Conform's [`parseSubmission`](https://conform.guide/api/react/future/parseSubmission) future API when parsing `FormData` or `URLSearchParams` submissions with many unique field names. The parser previously looked up values by field name, which could require repeated scans of the submitted entries and cause excessive synchronous CPU work if an attacker supplies a crafted submission.

> [!NOTE] > The patched version fixes this by iterating submitted entries directly instead of repeatedly looking up values by field name. Applications that accept untrusted form submissions should still enforce request parsing limits before passing data to Conform. For multipart requests, [@remix-run/form-data-parser](https://www.npmjs.com/package/@remix-run/form-data-parser) provides `maxParts`, `maxTotalSize`, `maxFileSize`, `maxFiles`, and `maxHeaderSize` options.