RCE in Vbulletin
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.
EPSS: 0.708 (99.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Vbulletin — versions 5.0.0, 6.0.0, 6.2.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com
- disclosure@vulncheck.com
- disclosure@vulncheck.com (third-party-advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2026-61511?
- CVE-2026-61511 is a critical-severity vulnerability in Vbulletin, classified under Eval Injection. CVSS score: 9.8/10. Published 2026-07-27.
- How severe is CVE-2026-61511?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2026-61511 known to be exploited?
- 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.