CVE-2026-61511

vBulletin 5.x through 5.7.5 and 6.x through 6.2.1 contains an eval injection vulnerability in the vB5_Template_Runtime::runMaths() method within the template runtime that allows unauthenticated remote attackers to execute arbitrary PHP code by supplying crafted input through the pagenav[pagenumber] parameter. Attackers can exploit the insufficiently restrictive regex filter by using phpfuck-style encoding with permitted characters to inject and execute arbitrary PHP code via the unauthenticated ajax/render template route without any authentication.

CVSS 4.0

9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

5.6% chance of exploitation in the next 30 days; higher than 92% of CVEs (scores of 2026-10-25)

CWE

CWE-95

Published

2026-07-27

Modified

2026-10-14

Record from

the NVD, synced 2026-10-19

References

• https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4509358-security-patch-released-for-vbulletin-6-2-1-6-2-0-and-6-1-6
• https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4509404-vbulletin-6-2-2-is-available
• https://karmainsecurity.com/KIS-2026-13
• https://ssd-disclosure.com/vbulletin-runtime-template-runmaths-preauth-rce/
• https://www.vulncheck.com/advisories/vbulletin-eval-injection-rce-via-vb5-template-runtime-php

Check your stackJSON