CVE-2025-6742: Brainstormforce Sureforms RCE Vulnerability

CVE-2025-6742 Overview

CVE-2025-6742 is a PHP Object Injection vulnerability in the SureForms – Drag and Drop Form Builder plugin for WordPress, developed by Brainstormforce. The flaw affects all versions of sureforms up to and including 1.7.3. The vulnerability resides in the delete_entry_files() function, which calls file_exists() on attacker-controlled input without restricting the path. Unauthenticated attackers can inject a PHP object through this entry point. SureForms itself does not ship a Property-Oriented Programming (POP) chain, so exploitation requires another installed plugin or theme to provide a gadget chain. When such a chain is present, attackers may delete arbitrary files, exfiltrate sensitive data, or execute arbitrary code.

Critical Impact

Unauthenticated PHP Object Injection in delete_entry_files() can chain with third-party POP gadgets to achieve remote code execution, arbitrary file deletion, or sensitive data disclosure on affected WordPress sites.

Affected Products

• Brainstormforce SureForms plugin for WordPress, all versions up to and including 1.7.3
• WordPress installations using sureforms with any additional plugin or theme containing a usable POP chain
• SureForms version 1.5.0 is explicitly enumerated in the CPE data as affected

Discovery Timeline

• 2025-07-09 - CVE-2025-6742 published to the National Vulnerability Database (NVD)
• 2025-07-11 - Last updated in the NVD database

Technical Details for CVE-2025-6742

Vulnerability Analysis

The vulnerability is classified as Insecure Deserialization [CWE-502]. The SureForms plugin processes user-supplied input within the delete_entry_files() function and passes it into PHP's file_exists() without sanitization or path restriction. In PHP, certain stream wrappers and serialization contexts can trigger object instantiation when string inputs are evaluated, enabling object injection through unsanitized data flows reaching deserialization or reflection-like sinks. Because the entry point requires no authentication, any unauthenticated network attacker can submit crafted input to the vulnerable handler. The attack complexity is elevated because successful exploitation depends on a usable POP chain existing in another installed plugin or theme on the target site.

Root Cause

The root cause is improper validation of attacker-controlled data passed to a function that can trigger PHP object instantiation. The delete_entry_files() function trusts the supplied path and does not constrain it to an allowlist, expected directory, or sanitized format. This permits serialized object payloads or wrapper-prefixed strings to flow into a sensitive PHP API.

Attack Vector

An unauthenticated attacker sends a crafted HTTP request to the WordPress endpoint that invokes delete_entry_files(). The supplied path parameter contains the object injection payload. When file_exists() processes the payload, PHP may instantiate attacker-defined objects. If a plugin or theme on the site exposes a magic method such as __destruct(), __wakeup(), or __toString() with exploitable side effects, those methods execute during object lifecycle events, completing the POP chain.

No public proof-of-concept code has been verified for this issue. Refer to the Wordfence Vulnerability Analysis for additional technical context and the WordPress Changeset Update for the patch diff.

Detection Methods for CVE-2025-6742

Indicators of Compromise

• HTTP requests to SureForms entry-handling endpoints containing serialized PHP object markers such as O: or a: followed by integer:string patterns
• Requests targeting delete_entry_files() parameters with stream wrapper prefixes such as phar://, php://, or data://
• Unexpected deletion of files within the WordPress installation directory after SureForms request traffic
• New or modified PHP files in wp-content/uploads/ or plugin directories following anonymous POST traffic

Detection Strategies

• Inspect web server access logs for unauthenticated POST requests to SureForms endpoints carrying long URL-encoded payloads matching PHP serialization grammar
• Deploy web application firewall (WAF) rules that flag serialized PHP object signatures and phar:// wrapper usage in request bodies and query strings
• Correlate WordPress audit logs with file system change events to identify unauthorized deletions or writes triggered by SureForms request flows

Monitoring Recommendations

• Enable file integrity monitoring on wp-content/plugins/sureforms/ and the broader WordPress document root
• Track outbound network connections initiated by the PHP-FPM or web server process immediately after SureForms requests, which can indicate post-exploitation activity
• Alert on installation of new plugins or themes on production sites, as additional components introduce potential POP gadgets that activate this vulnerability

How to Mitigate CVE-2025-6742

Immediate Actions Required

• Update the SureForms plugin to a version newer than 1.7.3 that contains the fix committed in changeset 3319753
• Audit all installed plugins and themes for known POP chain gadgets and remove unused components to reduce exposure
• Block requests containing PHP serialization patterns and phar:// wrappers at the WAF or reverse proxy layer
• Review WordPress file system and entry tables for evidence of prior exploitation before patching

Patch Information

The vendor addressed the issue in the SureForms plugin via the WordPress Changeset Update. Administrators should install the patched release available from the SureForms Plugin Page and confirm the running version is greater than 1.7.3.

Workarounds

• If immediate patching is not possible, deactivate the SureForms plugin until the update is applied
• Restrict access to SureForms entry endpoints using server-level access control rules or authentication requirements
• Disable the phar stream wrapper in PHP configuration where application functionality permits

# Example PHP hardening: disable phar wrapper in php.ini
phar.readonly = On
disable_functions = "phar_read,unserialize"
allow_url_include = Off