# CVE-2026-61511: vBulletin < 6.2.2 Eval Injection RCE via vb5/template/runtime.php

- Exploited (CISA KEV): no
- Published: 2026-07-27
- CVSS: 9.3 CRITICAL (v4.0)
- EPSS: 5.6% (93th percentile)
- CWE: CWE-95

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2026-08-11 | 15 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2026-09-16 | 51 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2026-08-11 · new · rule 1b0775f0f092483387cfb23f94f3006b · default Block
  > vBulletin - Remote Code Execution - CVE:CVE-2026-61511. Previous action: Log. New action: Block. This is a new detection.
  Source: https://developers.cloudflare.com/changelog/post/2026-08-11-waf-release/

### F5

- 2026-09-16 · new · rule 200204088
  > Added: signature 200204088 "vBulletin Math Template Remote Code Execution" (Server Side Code Injection, risk High), systems: PHP. References: CVE-2026-61511.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: passed (0 of 1 requests blocked), template CVE-2026-61511, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2026-61511, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2026-61511 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2026-61511