vBulletin: vBulletin template engine arbitrary PHP code execution (CVE-2025-48828) #shorts

Summary

CVE-2025-48828 is a critical remote code execution vulnerability in vBulletin 6.0.3 discovered and published on May 27, 2025. Attackers can abuse the template engine’s conditional syntax to execute arbitrary PHP code. Exploits were observed in the wild shortly after disclosure, highlighting the urgency of timely patching.

Product details

The vulnerability affects vBulletin version 6.0.3 (custom builds included). vBulletin is a widely used PHP-based forum and community platform. Administrators running this version or custom derivatives are at risk.

Vulnerability type summary

CWE-424: Improper Protection of Alternate Path. The issue arises because the template engine fails to validate alternate invocation syntax, allowing attackers to invoke PHP functions directly from templates.

Details of the vulnerability

The vBulletin template engine supports conditional constructs. By crafting template code using an alternate PHP function invocation syntax— for example, writing var_dump("test") within a template conditional—attackers bypass internal security checks. This leads to execution of arbitrary PHP functions and code. The flaw was demonstrated and exploited in May 2025 as part of mass scanning campaigns. Both Egidio Romano and Ryan Dewhurst publicly disclosed related vBulletin template vulnerabilities (CVE-2025-48827 and CVE-2025-48828), underscoring gaps in patch management and update practices.

Conclusion

Administrators should immediately update vBulletin installations to the patched version. Review template code for untrusted inputs and enforce strict function invocation checks. Regularly monitor for security advisories and apply updates promptly to mitigate emerging threats.

Watch the full video on YouTube: CVE-2025-48828

Remediation and exploitation details

This chain involves the following actors

  • Malicious user: Attacker who exploits the template engine
  • Forum administrator: Responsible for installing, updating and patching vBulletin

This following systems are involved

  • vBulletin 6.0.3 (Web-based discussion forum platform): Target of the injected PHP code

Attack entry point

  • Template conditional processor: Module that parses and evaluates conditional statements in forum templates

Remediation actions

Forum administrator
Apply the official security patch or upgrade to vBulletin 6.0.4 or later
vBulletin 6.0.3
Forum administrator
Review custom templates and remove or sanitize untrusted code snippets
vBulletin template engine

Exploitation actions

Abuse of template editing feature

Malicious user
Locate or gain access to the template editor in the forum control panel
vBulletin 6.0.3
Examples:
  • Log in with low-privilege account that can edit a public skin or widget
  • Navigate to Styles & Templates > Search in Templates

Alternate function invocation bypass

Malicious user
Insert a crafted conditional using alternate PHP function call syntax to bypass safety filters
Template conditional processor
Examples:
  • {if var_dump('test')}…{/if}
  • {vb:if var_dump('test')}{vb:else}{/vb:if}

Arbitrary code injection

Malicious user
Embed a system command or PHP payload inside the function call
Template conditional processor
Examples:
  • {if var_dump(shell_exec('id'))}{/if}
  • {if var_dump(system('ls -la /var/www'))}{/if}

Trigger code execution on the server

Malicious user
Save the modified template and view the page that uses it
vBulletin page renderer
Examples:
  • Open the forum section or widget that references the tampered template
  • Observe the output of the injected shell command in the page response

Related Content

NOTE: The following related content has not been vetted and may be unsafe.

CVE database technical details

CVE ID
CVE-2025-48828
Description
Certain vBulletin versions might allow attackers to execute arbitrary PHP code by abusing Template Conditionals in the template engine. By crafting template code in an alternative PHP function invocation syntax, such as the "var_dump"("test") syntax, attackers can bypass security checks and execute arbitrary PHP code, as exploited in the wild in May 2025.
Provider
mitre
CWE / problem types
CWE-424 Improper Protection of Alternate Path
Affected Software Versions
vBulletin:vBulletin:[{'status': 'affected', 'version': '6.0.3', 'versionType': 'custom'}]
Date Published
2025-05-27T00:00:00.000Z
Last Updated
2025-05-27T18:04:16.774Z