CVE-2025-48828

What it actually does

This vulnerability allows arbitrary PHP code execution through the vBulletin template engine. The flaw is in the handling of Template Conditionals: security checks intended to restrict dangerous PHP execution can be bypassed by using alternative PHP function invocation syntax, for example calling a function as "function_name"("argument"). If an attacker can inject or modify template code that is later rendered by vBulletin, the application may execute attacker-controlled PHP in the context of the web server process. Technical consequences can include command execution, web shell deployment, credential theft, database access through the application, modification of forum content, and full compromise of the vBulletin instance.

Why it matters to the business

A successful exploit can turn a public forum or community site into an attacker-controlled server. This can cause service disruption, defacement, theft of user data, theft of administrator credentials, malware hosting, spam distribution, and further intrusion into connected infrastructure. The EPSS score is high and the exploit is described as weaponized with exploitation observed in the wild in May 2025, so internet-facing vBulletin deployments should be treated as high-priority exposure even though this CVE is not currently listed in CISA KEV.

How an attack unfolds

An attacker identifies a vulnerable vBulletin deployment and determines whether they can reach a code path that accepts or processes template code. They then craft a malicious template conditional that uses alternative PHP invocation syntax, such as quoting the function name before calling it, to bypass the template engine’s filtering logic. When the vulnerable template is saved, previewed, rendered, or otherwise evaluated by the application, vBulletin executes the embedded PHP function. In real attacks, the initial payload is likely to be a lightweight proof of execution, followed by commands that write a PHP web shell, create persistence through template changes, harvest configuration secrets, or execute operating system commands under the web server account. Because exploitation has been observed in the wild and exploit maturity is weaponized, defenders should assume automated scanning and opportunistic compromise are plausible for exposed instances.

How to fix it

Upgrade vBulletin to a vendor-supported fixed release as soon as a fixed version applicable to the deployed branch is available. Because no exact fixed versions were provided in the input, verify the appropriate patched release directly from the vBulletin vendor advisory or support portal and apply all associated template-engine security patches. If immediate patching is not possible, restrict administrative and template-management interfaces to trusted IP addresses or VPN access, disable or tightly control template editing/import features where operationally feasible, remove unnecessary administrator accounts, enforce MFA for administrative access, and place the site behind a WAF rule set that blocks suspicious template payloads containing quoted PHP function calls and dangerous PHP functions. Review and remove unauthorized template changes after patching, because malicious template code may persist across upgrades if not cleaned up.

How to confirm the fix worked

Confirm the installed vBulletin version and build against the vendor’s patched release information for this issue. Verify that all application files, plugins, and templates were updated or rebuilt as required by the vendor. Review template content for suspicious PHP-like function calls, especially quoted function invocation syntax such as "system"(...), "shell_exec"(...), or "var_dump"(...). Test that template conditional input no longer permits execution of arbitrary PHP functions by using a safe, non-destructive test in a staging environment only. Confirm administrative/template-management paths are restricted as intended and that unauthenticated or low-privileged users cannot submit template code. After remediation, monitor logs for continued exploitation attempts, because public exploitation has already been reported.

Typical attack path

1. Discover an internet-facing vBulletin forum or community site and fingerprint the product/version or template behavior.
2. Reach a vulnerable template-processing workflow, such as a template edit, import, preview, rendering, or other feature that evaluates Template Conditionals.
3. Submit template code using alternative PHP function invocation syntax, for example a quoted function name followed by parentheses.
4. Trigger rendering or evaluation of the malicious template so the PHP function executes on the server.
5. Run reconnaissance commands to identify the application path, user privileges, PHP version, and writable directories.
6. Deploy a PHP web shell or modify templates to preserve code-execution capability.
7. Access application configuration files, secrets, user data, or administrator sessions.
8. Use the compromised web server for lateral movement, spam, malware hosting, defacement, or further persistence.

How to detect it

To determine whether exploitation already occurred, review web server access logs, error logs, PHP logs, vBulletin application logs, administrative audit logs, and file integrity monitoring data. Focus on requests to administrative, template-editing, template-import, preview, plugin, or style-management functionality that contain PHP-like function names or unusual quoted function calls. Look for HTTP POST requests containing strings such as "var_dump"(, "system"(, "shell_exec"(, "passthru"(, "exec"(, "assert"(, base64_decode, or eval-like payloads. Review template histories and current template content for unauthorized edits, especially changes that include command-execution functions, encoded payloads, or external network fetches. Examine the web root and writable upload/cache directories for recently created PHP files, files with image extensions containing PHP code, or small web shells. Correlate suspicious requests with subsequent 200 responses, PHP errors, new files, new administrator logins, outbound connections from the web server, or command execution artifacts. Because exploitation was reported in the wild in May 2025, include historical logs from at least that period where available.

• "var_dump"("test")
• "var_dump"(
• "system"(
• "shell_exec"(
• "passthru"(
• "exec"(
• "assert"(
• "popen"(
• "proc_open"(
• base64_decode(
• eval(
• /admincp/template.php
• template.php?do=
• cmd=
• /tmp/
• c99.php
• r57.php
• wso.php
• b374k.php
• FilesMan

What your security team should do

• Immediately inventory all internet-facing vBulletin deployments and determine whether they run an affected, unpatched version.
• Patch or upgrade exposed vBulletin systems on an emergency timeline due to weaponized exploitation and high EPSS likelihood.
• Before and after patching, review templates for suspicious quoted PHP function calls and unauthorized recent modifications.
• Restrict access to administrative and template-management interfaces to trusted networks or VPN users only.
• Search web, application, PHP, and web server logs for exploitation attempts and post-exploitation activity beginning before May 2025 and continuing to the present.
• Hunt for newly created PHP files, web shells, unexpected template changes, unknown administrator accounts, and suspicious outbound connections from the web server.
• Rotate credentials and secrets accessible to the vBulletin application if compromise is suspected, including database credentials, administrator passwords, API keys, and mail credentials.
• Add WAF/SIEM detections for quoted PHP function invocation patterns and dangerous PHP function names appearing in HTTP requests or template content.
• Preserve forensic evidence before rebuilding or cleaning systems where exploitation indicators are found.