CVE-2026-61511
CRITICALEPSS 75th pctlDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Elevated risk: more likely to be exploited than 75% of all known CVEs.
References
Related Vulnerabilities
Other CWE-95 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-24893 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2026-33017 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2024-36401 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2024-21650 | Critical | 10.0 | 93% | - | - |
| CVE-2023-37462 | Critical | 9.9 | 91% | - | Fix |
| CVE-2024-7954 | Critical | 9.8 | 90% | - | Fix |
Common questions
How do I fix CVE-2026-61511?
No published fix for CVE-2026-61511 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-61511 being actively exploited?
Not that we know of. CVE-2026-61511 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 75% of all scored CVEs.
How severe is CVE-2026-61511?
CVE-2026-61511 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
Embed a live status badge for CVE-2026-61511
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-07.