SVG files can not be uploaded if mimeTypes property is present

[akantic]

Describe the Bug

Hi, I've encountered an issue with uploading SVG files after updating the Payload version.

My mimeTypes configuration is the following:

    mimeTypes: [
      'image/*',
      'video/*',
      'application/pdf',
      'application/msword',
      'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
      'application/vnd.ms-excel',
      'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
    ],

but I started getting an error File buffer returned no detectable MIME type. when trying to save the media.

I dig into payload source and located the issue, the issue is located at packages/payload/src/uploads/checkFileRestrictions.ts, at line 83, where file type is expected from the fileTypeFromBuffer function. However, file-type library clearly mentions in its README that it does not work for text-based formats, including .svg.

This results in undefined value for detected variable and fails right there with an error.

I also tried this in a minimal setup without Payload, with the same result.

import { fileTypeFromBuffer } from "file-type";
import fs from "fs";
import path from "path";
import { fileURLToPath } from "url";

const filePath = path.join(
  path.dirname(fileURLToPath(import.meta.url)),
  "test-file.svg"
);
const buffer = fs.readFileSync(filePath);
const fileType = await fileTypeFromBuffer(buffer);

console.log(fileType); // outputs undefined

I think file-type's functionality must be extended, as textual formats are quite common, especially in a generic CMS system like Payload.

Link to the code that reproduces this issue

https://github.com/akantic/payload-issue-mime-type-svg

Reproduction Steps

1. Clone
2. pnpm install & pnpm dev
3. Login with test@payload.com / test123
4. Try to upload an svg file into Media collection.

Which area(s) are affected? (Select all that apply)

area: core

Environment Info

Binaries:
  Node: 20.18.1
  npm: 10.8.2
  Yarn: 1.22.22
  pnpm: 10.10.0
Relevant Packages:
  payload: 3.65.0
  next: 15.4.7
  @payloadcms/db-sqlite: 3.65.0
  @payloadcms/drizzle: 3.65.0
  @payloadcms/graphql: 3.65.0
  @payloadcms/next/utilities: 3.65.0
  @payloadcms/richtext-lexical: 3.65.0
  @payloadcms/translations: 3.65.0
  @payloadcms/ui/shared: 3.65.0
  react: 19.1.0
  react-dom: 19.1.0
Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.4.0: Fri Apr 11 18:33:47 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T6000
  Available memory (MB): 32768
  Available CPU cores: 10

[basilsaman-aufait]

Detected the same issue

[github-actions]

🚀 This is included in version v3.66.0