CVE-2026-61511
CriticalExploitedPublic exploitvBulletin 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…
Published Jul 27, 2026 · Updated Oct 14, 2026
Key Facts
Patch immediately- CVE-2026-61511 is a critical-severity vulnerability (CVSS 9.3 v4) affecting vBulletin.
- It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Aug 27, 2026. Public exploit code is available.
- EPSS estimates a 5.6% probability of exploitation in the next 30 days.
- Fixed versions are available, including vBulletin 5.7.5.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v4
9.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
EPSS (30-day exploit likelihood)
5.6%
Higher than 92.8% of all scored CVEs
Exploited in the wild
Yes
2 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-61511 brief as a PDF
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Description
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Aug 27, 2026 | n/a | Not reported |
| CIRCL KEV | Aug 27, 2026 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| vBulletinVbulletin | >= 5.0.0 | 5.7.5 |
Patched Releases
vBulletin
5.7.5
Timeline
Publicly disclosed
Jul 27, 2026
Added to Industry KEV feed
Aug 27, 2026
Added to CIRCL KEV
Aug 27, 2026
Last updated
Oct 14, 2026
Weakness Type
- CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
References
- exploitVulnCheck exploitation report
- otherhttp://seclists.org/fulldisclosure/2026/Aug/29
- other6.2.1, 6.2.0, 6.1.6 Security Announcement
- other6.2.2 Release Notes
- otherKarma(In)Security Disclosure
FAQ
Common Questions.
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.
Affected: vBulletin versions >= 5.0.0. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Aug 27, 2026.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including vBulletin 5.7.5.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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