GHSA-q4f2-39gr-45jh

Описание

Summary

Adminer v5.4.1 has a version check mechanism where adminer.org sends signed version info via JavaScript postMessage, which the browser then POSTs to ?script=version. This endpoint lacks origin validation and accepts POST data from any source. An attacker can POST version[] parameter which PHP converts to an array. On next page load, openssl_verify() receives this array instead of string and throws TypeError, returning HTTP 500 to all users.

Fix

Upgrade to Adminer 5.4.2.

Mitigation (if you can't upgrade): Make file adminer.version in temp directory (usually the value of upload_tmp_dir) unwritable by web server.

Details

1. Intended design of ?script=version:

The endpoint is designed to receive version data from adminer.org via browser JavaScript:

• functions.js line 102-117: Creates iframe to https://www.adminer.org/version/
• Adminer.org sends signed version data via postMessage
• JavaScript POSTs this to ?script=version
• Server stores in /tmp/adminer.version for signature verification

2. The vulnerability:

The endpoint only checks $_GET["script"] == "version" - it does not validate:

• Request origin (no CSRF token check for this endpoint)
• Request source (any HTTP client can POST)
• Parameter types (version expected as string, array not rejected)

3. Type confusion crash:

When POST contains version[] instead of version, PHP creates an array. When Adminer reads this file and passes to openssl_verify():

PHP 8.x throws:

PoC

Steps to Reproduce:

Step 1: Verify Adminer is running and accessible.

Expected output:

Step 2: Send the malicious POST request. The version[] syntax causes PHP to create an array instead of a string.

Expected output: Empty response (no error).

Step 3: Access Adminer again to trigger the crash.

Expected output:

Step 4: (Optional) View the PHP error in server logs.

Step 5: (Optional) Inspect the poisoned file.

Expected output:

Recovery:

After deletion, Adminer returns HTTP 200.

Impact

Type: Denial of Service

Root cause: The ?script=version endpoint is designed to receive data from adminer.org via JavaScript, but lacks server-side validation. Any HTTP client can POST directly to this endpoint. Combined with missing type validation before openssl_verify(), this allows persistent DoS.

Affected users: Any Adminer instance accessible over the network.