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 v4.0

9.3 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

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

EPSS

70.77% chance of exploitation in the next 30 days, 99th percentile

Nuclei

critical · CWE-94

Published

2026-07-27

Updated

2026-08-07

Proof-of-concept exploits (5)

• https://karmainsecurity.com/KIS-2026-13
• https://ssd-disclosure.com/vbulletin-runtime-template-runmaths-preauth-rce/
• HORKimhab/CVE-2026-615110★ · 2026-07-28
• shootcannon/CVE-2026-615110★ · 2026-07-30
• tc4dy/CVE-2026-61511-PoC-Exploit

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-61511.yaml

References

• CVE Record
• NVD entry

Related

• CVE-2026-4257
• CVE-2026-5076
• CVE-2026-0073
• CVE-2026-14762
• CVE-2026-15409
• CVE-2026-15410