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Home - Vulnerability NotesPrint
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CERT-In Vulnerability Note CIVN-2026-0391
Arbitrary Code Vulnerability in vBulletin

Original Issue Date:August 05, 2026

Severity Rating: CRITICAL

Software Affected

  • vBulletin versions from 5.0.0 through 5.7.5
  • vBulletin versions from 6.0.0 through 6.2.1

Overview

A vulnerability has been reported in vBulletin which could allow an unauthenticated remote attacker to execute arbitrary PHP code on the targeted system.

Target Audience:
All end-user organizations and individuals using VBulletin.

Impact Assessment:
Potential of complete compromise of system

Risk Assessment:
Remote unauthenticated exploitation may lead to complete system compromise.

Description

vBulletin is a commercial PHP-based forum software used to create and manage online discussion boards and community websites.

A vulnerability has been reported in vBulletin due to improper sanitization of user-supplied input in the runMaths() function, an unauthenticated attacker can exploit the flaw by sending a specially crafted request to the "ajax/render/[template]" endpoint.

Successful exploitation of the vulnerability could allow an unauthenticated remote attacker to execute arbitrary PHP code on the targeted system.

Solution

Apply appropriate updates as mentioned by the vendor
https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4509404-vbulletin-6-2-2-is-available

Vendor Information

vBulletin
https://www.vbulletin.com/

References

 
https://www.bleepingcomputer.com/news/security/vbulletin-fixes-critical-pre-auth-rce-flaw-with-public-exploit/

CVE Name
CVE-2026-61511

Disclaimer

The information provided herein is on "as is" basis, without warranty of any kind.

Contact Information

Email: info@cert-in.org.in
Phone: +91-11-22902657

Postal address

Indian Computer Emergency Response Team (CERT-In)
Ministry of Electronics and Information Technology
Government of India
Electronics Niketan
6, CGO Complex, Lodhi Road,
New Delhi - 110 003
India

 
Indian Computer Emergency Response Team - CERT-In, Ministry of Electronics and Information Technology, Government of India.
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